Top 100 Networking Interview Questions and Answers-(2024)

1 .

Networking can be defined as the process of connecting various devices or systems such as servers, desktops, laptops, smartphones, tablets connected through multiple paths for sending or receiving the data, applications and resources located on network nodes. The networking hardware includes devices such as network cables, routers, network cards and distributors etc,.

2 .

What is a link?

A link basically is the connection between two or more computers or devices. It can be anything depending on whether it is a physical connection or a wireless one. Physical links include cables, hubs, switches, etc and wireless links wireless access points, routers, etc.

3 .

What are the different types of networks?

Considering the size or span of a network, we can classify them as follows :

PAN (Personal Area Network) : PAN is made up of devices used by a single person. It has a range of a few meters.

WPAN (Wireless Personal Area Network) : It is a PAN network that uses wireless technologies as a medium.

LAN (Local Area Network) : LAN is a network whose range is limited to a relatively small area, such as a room, a building, an aeroplane, etc.

WLAN (Wireless Local Area Network) : WLAN is a LAN network that uses wireless means of communication. It is a widely used configuration due to its scalability and because it does not require the installation of cables.

CAN (Campus Area Network) : A network of high-speed devices that connects LANs in a limited geographical area, such as a university campus, a military base, etc.

MAN (Metropolitan Area Network) or metropolitan area network : It is a high-speed (broadband) network providing coverage in a larger geographic area than a campus, but still limited.

WAN (Wide Area Network) : WAN extends over a large geographical area using unusual means of communication, such as satellites, interoceanic cables, fibre optics, etc. Use public media.

VLAN : It is a type of logical or virtual LAN, mounted on a physical network, in order to increase security and performance. In special cases, thanks to the 802.11Q protocol (also called QinQ), it is possible to mount virtual networks on WAN networks. It is important not to confuse this implementation with VPN technology.
Network Types

4 .

What is a personal area network (PAN)?

A personal area network (PAN) connects electronic devices within a user's immediate area. The size of a PAN ranges from a few centimeters to a few meters. One of the most common real-world examples of a PAN is the connection between a Bluetooth earpiece and a smartphone. PANs can also connect laptops, tablets, printers, keyboards, and other computerized devices.

PAN network connections can either be wired or wireless. Wired connection methods include USB and FireWire; wireless connection methods include Bluetooth (the most common), WiFi, IrDA, and Zigbee.

While devices within a PAN can exchange data with each other, PANs typically do not include a router and thus do not connect to the Internet directly. A device within a PAN, however, can be connected to a local area network (LAN) that then connects to the Internet. For instance, a desktop computer, a wireless mouse, and wireless headphones can all be connected to each other, but only the computer can connect directly to the Internet.

5 .

What Is a Local Area Network (LAN)?

A Local Area Network (LAN) is a collection of devices connected together in one physical location, such as a building, office, or home. A LAN can be small or large, ranging from a home network with one user to an enterprise network with thousands of users and devices in an office or school.

A LAN comprises cables, access points, switches, routers, and other components that enable devices to connect to internal servers, web servers, and other LANs via wide area networks.

The rise of virtualization has also fueled the development of virtual LANs, which enable network administrators to logically group network nodes and partition their networks without a need for major infrastructure changes.

For example, in an office with multiple departments, such as accounting, IT support, and administration, each department's computers could be logically connected to the same switch but segmented to behave as if they are separate.

6 .

What are the benefits of a LAN?

The advantages of a LAN are the same as those for any group of devices networked together. The devices can use a single Internet connection, share files with one another, print to shared printers, and be accessed and even controlled by one another.

LANs were developed in the 1960s for use by colleges, universities, and research facilities (such as NASA), primarily to connect computers to other computers. It wasn't until the development of Ethernet technology (1973, at Xerox PARC), its commercialization (1980), and its standardization (1983) that LANs started to be used widely.

While the benefits of having devices connected to a network have always been well understood, it wasn't until the wide deployment of Wi-Fi technology that LANs became commonplace in nearly every type of environment. Today, not only do businesses and schools use LANs, but also restaurants, coffee shops, stores, and homes.

Wireless connectivity has also greatly expanded the types of devices that can be connected to a LAN. Now, nearly everything imaginable can be "connected," from PCs, printers, and phones to smart TVs, stereos, speakers, lighting, thermostats, window shades, door locks, security cameras--and even coffeemakers, refrigerators, and toys.

7 .

Are there different types of LANs?

In general, there are two types of LANs :

* client/server LANs
* peer-to-peer LANs.

A client/server LAN consists of several devices (the clients) connected to a central server. The server manages file storage, application access, device access, and network traffic. A client can be any connected device that runs or accesses applications or the Internet. The clients connect to the server either with cables or through wireless connections.

Typically, suites of applications can be kept on the LAN server. Users can access databases, email, document sharing, printing, and other services through applications running on the LAN server, with read and write access maintained by a network or IT administrator. Most midsize to large business, government, research, and education networks are client/server-based LANs.

A peer-to-peer LAN doesn't have a central server and cannot handle heavy workloads like a client/server LAN can, and so they're typically smaller. On a peer-to-peer LAN, each device shares equally in the functioning of the network. The devices share resources and data through wired or wireless connections to a switch or router. Most home networks are peer-to-peer.

Source : CISCO

8 .

What is a wide area network (WAN)?

A wide area network (WAN) is a large computer network that connects groups of computers over large distances. WANs are often used by large businesses to connect their office networks; each office typically has its own local area network, or LAN, and these LANs connect via a WAN. These long connections may be formed in several different ways, including leased lines, VPNs, or IP tunnels (see below).

The definition of what constitutes a WAN is fairly broad. Technically, any large network that spreads out over a wide geographic area is a WAN. The Internet itself is considered a WAN.

Wide Area Networking

Source : Cloudflare

9 .

What is a metropolitan area network (MAN)?

Metropolitan Area Network (MAN) is a broadband telecommunication network that connects several LANs in close proximity. As a rule, these are individual establishments in a company that are connected to a MAN via leased lines. High-performance routers and high-performance fiber-based connections are used, which enable a significantly higher data throughput than the internet. The transfer speed between two remote nodes is comparable to that of communication within a LAN.

The infrastructure for MANs is provided by international network operators. As a Metropolitan Area Network, wired cities can be integrated nationally into Wide Area Networks (WAN) and internationally in Global Area Networks (GAN).

With Metro Ethernet, a special transmission technology is available for MANs, which can be used to build powerful Metro Ethernet networks (MEN) based on Carrier Ethernet (CE 1.0) or Carrier Ethernet 2.0 (CE 2.0).

A standard for larger regional radio networks, known as Wireless Metropolitan Area Networks (WMAN), was developed with IEEE 802.16. This technology known as WiMAX (Worldwide Interoperability for Microwave Access) makes it possible to set up WiFi hotspots. These are several WiFi access points working together in different locations. The current transmission standard DSL is technically only available where copper cables have been laid.

10 .

How are MAN networks constructed?

Like WANs, a MAN is made up of interconnected LANs. Because MANs are smaller, they are usually more efficient than WANs, since data does not have to travel over large distances. MANs typically combine the networks of multiple organizations, instead of being managed by a single organization.

Most MANs use fiber optic cables to form connections between LANs. Often a MAN will run on "dark fiber" — formerly unused fiber optic cables that are able to carry traffic. These fiber optic cables may be leased from private-sector Internet service providers (ISP).

In some cases, this model is reversed: a city government builds and maintains a metropolitan fiber optic network, then leases dark fiber to private companies.

11 .

What is Global Area Network (GAN)?

A global network, such as the internet, is referred to as the Globe Area Network (GAN). The internet is, however, not the only computer network of its kind. Internationally operating companies also support local networks that comprise of several WANs and connect company computers across the world. GANs use the fiber optic infrastructure from wide area networks and combine these with international undersea cables or satellite transmissions.

12 .

What is Virtual Private Network (VPN)?

A Virtual Privat Network (VPN) is a virtual communication network that uses the infrastructure of a physical network to logically connect computer systems. This can be any of the network types introduced above, however, the internet is the most common transport medium. This connects nearly all computers worldwide and is available free of charge, as opposed to privately operated MANs or WANs. Data transfer takes place within a virtual tunnel, which is built between a VPN client and a VPN server.

If the public network is used as a transport medium, Virtual Private Networks are generally encrypted to ensure that data stays confidential. VPNs are utilized to link LANs over the internet or to enable remote access to a network or a single computer via public connection.

VPN

Source : IONOS

13 .

Explain some Application areas of Virtual Private Networks.

Generally, VPNs are used for one of the following three main reasons: to interconnect two or more company locations via a public network (site-to-site VPN), to remotely access the company network when traveling or from home (end-to-site VPN), or to remotely access one computer from another computer (end-to-end VPN).

Site-to-Site VPN : A site-to-site VPN is used when multiple local networks are to be connected to a virtual communication network, via a public transport medium. Such scenarios are possible, for example, when connecting different company locations with one another. Alternatively, location networks can also be realized, in the form of a corporate network. Corporate networks are based on a private fixed connection, but companies have to rent the corresponding infrastructure first in order to use it. A connection via VPN, on the other hand, relies on a public network. Here an internet connection is the only cost involved. Creating a site-to-site VPN also requires a VPN router; these are needed to build the connection between the VPN tunnel and the local network. Other terms used to describe a site-to-site VPN include: LAN-to-LAN or Branch-Office VPNs.

End-to-Site-VPN : Companies tend to use end-to-end VPNs whenever their networks are to be made available for mobile users working in the field of from their home offices. The tunnel to the local network is created through a VPN client on the external employee’s terminal device; here the main transport medium is also the internet. This enables employees to access the company network (and so any file and mail server located within this) simply via internet connection. An end-to-site VPN is also referred to as a remote-access VPN.

End-to-End VPN : And end-to-end VPN occurs if setting up a network with remote access isn’t possible, and can only be done by connecting one computer to another one. Working on a remote desktop would be a classic use case for this kind of VPN connection. Here, a software program is executed on one computer, and displayed and used on another one. The transport medium for such applications can be the internet or a local company network. For business-related purposes, remote desktop VPNs are used when an employee seeks to access their work computer from home.

14 .

How to Implementing a Virtual Private Network?

Many different protocols are used when implementing an encrypted connection via VPN. The most common solutions rely on IPSec, L2TP over IPSec, and SSL.

VPN with IPsec : ‘Internet protocol security’ (IPSec) is a protocol suite designed for the internet protocol (IP) with version 6 (IPv6) and enables secure communication via non-trustworthy IP networks. Encryption and authentication mechanisms help ensure that the data traffic’s privacy, authenticity, and integrity are safeguarded. IPSec was developed with IPv6 and was retroactively specified for IPv4.

L2TP over IPSec : A VPN implemented with LTOP over IPSec uses the ‘Layer 2 Tunneling Protocol’ (L2TP). L2TP alone doesn’t contain any encryption. For this reason, the protocol is normally combined with IPSec. While IPSec is only able to tunnel IP packets, L2TP supports a variety of packet-transferring protocols. The combination L2TP over IPSec combines the strengths of both standards. The result is a highly secure and flexible tunneling protocol.

SSL-VPN : SSL was originally developed for use within HTTP environments. This is why the encryption protocol is used for securing VPN connections. Open VPN is a popular software solution for setting up a virtual private network.

15 .

What are the advantages of using a VPN?

Below are few advantages of using VPN :

* VPN is used to connect offices in different geographical locations remotely and is cheaper when compared to WAN connections.

* VPN is used for secure transactions and confidential data transfer between multiple offices located in different geographical locations.

* VPN keeps an organization’s information secured against any potential threats or intrusions by using virtualization.

* VPN encrypts the internet traffic and disguises the online identity.

16 .

What are nodes and links?

Node: Any communicating device in a network is called a Node. Node is the point of intersection in a network. It can send/receive data and information within a network. Examples of the node can be computers, laptops, printers, servers, modems, etc.

Link: A link or edge refers to the connectivity between two nodes in the network. It includes the type of connectivity (wired or wireless) between the nodes and protocols used for one node to be able to communicate with the other.

17 .

What is the network topology?

Network topology is the arrangement of a network that comprises nodes and connecting lines via sender and receiver is referred to as network topology. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

The various network topologies are :

* Bus Topology

* Star Topology

* Ring Topology
* Mesh Topology

* Tree Topology

* Hybrid Topology

18 .

What is Bus Topology?

Bus topology is a network type in which every computer and network device is connected to a single cable. It transmits the data from one end to another in a single direction. No bi-directional feature is in bus topology. It is a multi-point connection and a non-robust topology because if the backbone fails the topology crashes.

Advantages of this topology :

* If N devices are connected to each other in a bus topology, then the number of cables required to connect them is 1, which is known as backbone cable, and N drop lines are required.

* The cost of the cable is less as compared to other topologies, but it is used to build small networks.

Problems with this topology :

* If the common cable fails, then the whole system will crash down.

* If the network traffic is heavy, it increases collisions in the network. To avoid this, various protocols are used in the MAC layer known as Pure Aloha, Slotted Aloha, CSMA/CD, etc.

* Security is very low.

19 .

What is Star Topology?

In star topology, all the devices are connected to a single hub through a cable. This hub is the central node and all other nodes are connected to the central node. The hub can be passive in nature i.e., not an intelligent hub such as broadcasting devices, at the same time the hub can be intelligent known as an active hub. Active hubs have repeaters in them.

Advantages of this topology :

* If N devices are connected to each other in a star topology, then the number of cables required to connect them is N. So, it is easy to set up.

* Each device requires only 1 port i.e. to connect to the hub, therefore the total number of ports required is N.

Problems with this topology :

* If the concentrator (hub) on which the whole topology relies fails, the whole system will crash down.

* The cost of installation is high.

* Performance is based on the single concentrator i.e. hub.

20 .

What is Ring Topology?

In this topology, it forms a ring connecting devices with its exactly two neighboring devices.

A number of repeaters are used for Ring topology with a large number of nodes, because if someone wants to send some data to the last node in the ring topology with 100 nodes, then the data will have to pass through 99 nodes to reach the 100th node. Hence to prevent data loss repeaters are used in the network.

The transmission is unidirectional, but it can be made bidirectional by having 2 connections between each Network Node, it is called Dual Ring Topology.

The following operations take place in ring topology are :

* One station is known as a monitor station which takes all the responsibility to perform the operations.

* To transmit the data, the station has to hold the token. After the transmission is done, the token is to be released for other stations to use.

* When no station is transmitting the data, then the token will circulate in the ring.

* There are two types of token release techniques: Early token release releases the token just after transmitting the data and Delay token release releases the token after the acknowledgment is received from the receiver.

Advantages of this topology :

* The possibility of collision is minimum in this type of topology.

* Cheap to install and expand.

Problems with this topology :

* Troubleshooting is difficult in this topology.

* The addition of stations in between or removal of stations can disturb the whole topology.

* Less secure.

21 .

What is Mesh Topology?

In a mesh topology, every device is connected to another device via a particular channel.

Suppose, N number of devices are connected with each other in a mesh topology, the total number of ports that are required by each device is N-1. In Figure 1, there are 5 devices connected to each other, hence the total number of ports required by each device is 4. Total number of ports required=N*(N-1).

Suppose, N number of devices are connected with each other in a mesh topology, then the total number of dedicated links required to connect them is NC2 i.e. N(N-1)/2. In Figure 1, there are 5 devices connected to each other, hence the total number of links required is 5*4/2 = 10.

Advantages of this topology :

* It is robust.

* The fault is diagnosed easily. Data is reliable because data is transferred among the devices through dedicated channels or links.

* Provides security and privacy.

Problems with this topology :

* Installation and configuration are difficult.

* The cost of cables is high as bulk wiring is required, hence suitable for less number of devices.

* The cost of maintenance is high.

22 .

What is Tree Topology?

This topology is the variation of Star topology. This topology has a hierarchical flow of data.

In this, the various secondary hubs are connected to the central hub which contains the repeater. In this data flow from top to bottom i.e. from the central hub to secondary and then to the devices or from bottom to top i.e. devices to the secondary hub and then to the central hub. It is a multi-point connection and a non-robust topology because if the backbone fails the topology crashes.

Advantages of this topology :

* It allows more devices to be attached to a single central hub thus it decreases the distance that is traveled by the signal to come to the devices.

* It allows the network to get isolate and also prioritize from different computers.

Problems with this topology :

* If the central hub gets fails the entire system fails.

* The cost is high because of cabling.

23 .

What is Hybrid Topology?

A network structure whose design contains more than one topology is said to be hybrid topology. Hybrid topology inherits merits and demerits of all the incorporating topologies.

Image Source : tutorialspoint

The above picture represents an arbitrarily hybrid topology. The combining topologies may contain attributes of Star, Ring, Bus, and Daisy-chain topologies. Most WANs are connected by means of Dual-Ring topology and networks connected to them are mostly Star topology networks. Internet is the best example of largest Hybrid topology.

24 .

What is Switch in Networking?

A Switch in Networking is a small hardware device that connects multiple devices such as computers, printers, wireless access points, etc., within one local area network (LAN). It is the key building block of any network and enables the connected devices to send, receive or forward information with each other. A switch operates in layer 2, also known a the OSI model’s Data Link layer. Switches are the most commonly used component of networks based on Asynchronous Transfer Mode (ATM), Ethernet, InfiniBand, and more. These work by reducing the workload on the individual PCs and thereby increasing the overall bandwidth of the network. Switches use MAC addresses to support unicast, multicast, and broadcast communications to selected destination ports. These are broadly categorised into four types – Unmanaged switch, Managed switch, LAN switch, and PoE switch.

25 .

What is Router in Networking?

A Router is a networking device that sends, receives, and analyses data packets within the connected computer networks. A router is a layer three network device used in LAN (Local Area Network) and WAN (Wide Area Network) environments. When the data packet arrives, it inspects the destination IP address, consults its routing tables, calculates the best way to forward it and transfers it along the chosen route. Routers work on the routing protocol to prioritise the data to be transferred for each transmission. These are an essential part of modern computer networking, not just for establishing internet connections or data transmissions but also to provide additional security. By embedding firewalls and content filtering software, routers help businesses from malicious online websites and unwanted content. There are various routers available in the market depending upon their usages, such as wireless routers, edge routers, broadband routers, core routers and brouters.

26 .

What is Protocol in Networking?

A Protocol is an established set of rules that govern how devices exchange information within a network quickly and reliably. In other words, network protocols can be equated to a common language for two devices that enable them to have seamless communication, similar to how two people from different regions of the world may not understand each other’s native language but can still communicate using a ‘shared’ third language.

Protocols are often classified based on the OSI (Open Systems Interconnection) model layer they belong to. Some of the most important protocols used on the internet are :

* HTTP : The HyperText Transfer Protocol (HTTP) is an application layer protocol that provides the foundation for the World Wide Web.

* TCP : The Transmission Control Protocol (TCP) is a transport layer protocol used with IP and often referenced together as TCP/IP.

* TLS/SSL : Transport Layer Security is used for encryption and previously called Secure Sockets Layer (SSL)

27 .

What is a Firewall in Networking?

A Firewall is a network security device that monitors all incoming and outgoing traffic and permits, blocks, or drops data packets based on a defined set of security rules. In other words, a firewall establishes a barrier between your internal network and the incoming traffic from untrusted external sources such as the internet to block malicious traffics such as viruses and hacking.

A firewall can be implemented in the form of either a software or hardware device though it is best to have both. A software firewall is a program installed on your computer to regulate traffic through applications or port numbers. In contrast, a hardware firewall is a physical device installed between your network and gateway.

28 .

What is Gateway in Networking?

A Gateway is a networking hardware device that acts as a ‘gate’ to form a passage between two network devices with two high-level protocols. A gateway is a layer three network system or device used for both LAN and WAN interconnects to serve as a transitional task. In other words, it acts as a translator between two systems that use different languages, data formats, architectures, or communication protocols. The gateway acts as the entry and exit point for a network to manage the data inflows and outflows. It stores information about the routing paths of networks in communication and transmits data across them using the packet switching technique.

29 .

What is Hub in Networking?

A Hub is a networking device that allows you to connect multiple computing devices to a single network. It also acts as a multi-port repeater to amplify signals that deteriorate after travelling through a series of connecting cables. A hub has many ports to connect multiple wires from different branches. It can be used for both digital and analog data to broadcast messages primarily.

Hubs are passive physical devices that do not have any software associated with them. They are not intelligent devices and do not perform any message filtering. Hubs are mainly used in home networks or small organisations for network monitoring and connectivity.

There are two types of hubs – Active Hub and Passive Hub.

30 .

What is Bridge in Networking?

A Bridge is a networking device that connects multiple LANs to create a single, aggregated network segment. This process of aggregating networks to form a larger LAN is known as Network Bridging. Bridges work as the layer 2 network or data link layer of the OSI model and transmit data as data frames.

A wireless bridge connects networks having wireless segments. Bridges help improve network performance by separating a network into different sections or segments with different bandwidth. It can block or forward the incoming data frame after inspecting it for the destination MAC address. Switches are preferred over bridges in modern LANs as bridges generally connect fewer networks.

31 .

What is ARP in Networking?

The acronym ARP stands for Address Resolution Protocol (ARP) which is a communication protocol used to find the MAC (Media Access Control) address of a host from its IP address. It is an important protocol in networking used to convert a 32-bit Internet Protocol (IP) address, typically for IPv4, to a 48-bit MAC address in a LAN.

There are four types of ARP :

* Proxy ARP

* Gratuitous ARP

* Reverse ARP

* Inverse ARP

32 .

What is DNS in Networking?

DNS stands for Domain Name System, which, at its most basic, works like the phone book for the internet. You can think of DNS like your smartphone’s contact list, which matches contact’s names with their phone numbers and email addresses.

DNS is a hierarchical host naming system connected to the internet or any private network. The process involves converting the domain names of participating entities or hosts to a computer-friendly IP address.

DNS has been one of the foundations of the functionality of the internet since 1985. Though we don’t realise it, we use DNS to check our emails or while browsing on our smartphones every day. Whenever you connect to the internet, the DNS server that you use is automatically established by your network provider.

33 .

What is Ping in Networking?

A Ping is a software utility used to verify the reachability of a specific IP address on a network. It was first developed by Michael Muss in 1983 to quickly test various points of the network and get a response. It works by sending Internet Control Message Protocol (ICMP) echo requests to the host of a destination computer and then waiting for an echo reply. The ping is initiated several times to get responses echoed back to the source provides important information such as :

* consistency in the network connection

* bytes sent and received

* approximate duration of the round-trip time

* packets sent, received, or lost

34 .

What is Server in Networking?

A network server is computer hardware or software that acts as a central repository unit and provides data or information to other computers within the network. Hosting certain files or programs on one of the many networking servers enables users to access them by connecting to that server via LAN or WAN. There are many types of servers, such as web servers, email servers, file servers and more. A major advantage of this approach is that if a user loses their data, they can access their most important files stored on the network server. Additionally, multiple users can make changes to a single document or have access to shared devices such as a printer or a scanner. By offering a centralised location to store files, a network server helps improve file management and data security.

35 .

What is VLAN in Networking?

VLAN is a Virtual extension of LAN which works as a subnetwork for the collection of devices that communicate with one another within one logical network. The devices are physically apart but configured to communicate as if they are attached to the same wire. Implementing VLANs offers more flexibility than non-virtual network solutions and reduced security risks. It also helps in reducing traffic congestion as individual VLANs works as a separate LAN. Having a VLAN is cost-effective for organisations as it helps to expedite network operations and facilitates flexible teamwork.

36 .

What is NAT in Networking?

NAT is an acronym for Network Address Translation. It is a process of mapping multiple local private addresses to a public one inside a private network. It can be configured to assign only one address for the entire network for both security and economic purposes.

NAT allows a router to act as an interface between the public network or the internet and a private or local network. It can also be used to enable selective access outside the network and conserve private IP addresses used within an organisation hidden from the world.

37 .

What is a Router in Networking?

A Router is a networking device that connects two or more sub-networks or packet-switched networks. Most routers pass data traffic between LANs and WANs with the help of IP routing protocols.

A router is more capable than other network devices such as a hub or a switch. It analyses data sent over a network, determines its path and changes how it is packaged to send it over to a different network. Routers are most commonly used in home networking to connect multiple computers using a shared internet connection.

38 .

What is Port in Networking?

A Port is a communication endpoint in networking through which information flows from a program on the computer to another computer on the network. Think of a port as a docking point where all private boats are docked.

Ports are numbered, and each port is associated with a distinct service. They allow computers to differentiate between different kinds of incoming and outgoing traffic over the same network connection. Some ports are reserved for specific protocols, such as HTTP (HyperText Transfer Protocol) uses port 80, FTP (File Transport Protocol) uses port 21, emails received on a local computer use TCP port 25. Each host can have 65535 ports per IP address, and the use of these ports is managed by IANA (Internet Assigned Numbers Authority).

39 .

What is DHCP in Networking?

DHCP stands for Dynamic Host Configuration Protocol. It is a network protocol used on IP addresses to automate the process of configuring devices and allow for seamless communication on the network.

A DHCP server automatically assigns IP addresses to each host on the network, thus allowing them to use services such as DNS and any other communication protocol to communicate with other endpoints. This process simplifies the management of IP addresses on the same network and greatly reduces the errors made by manually assigning them. Using DHCP, IP conflicts are reduced, and it is easy to change addresses or endpoints.

40 .

What is Router in Networking and How it works?

A router is a virtual networking device that serves two main functions : receive, analyse and forward data packets to intended IP addresses and allow multiple computing devices to share the same internet connection.

How does it work?

A Router analyses the destination IP addresses of data packets and decide their routing path. To direct these data packets effectively, the router uses a routing protocol, compares it with its internal routing table and identifies the best path from the list to the network destination. It then forwards the data packet down the most efficient path to the given IP address. Routers also help to filter out unwanted interference, provides high-speed internet connectivity, allows users to configure ports as per their requirements and carry out data encapsulation or decapsulation processes.

41 .

What is Bandwidth in Networking?

The network bandwidth refers to the maximum transfer capacity of a wired or wireless network communication. In other words, it is a measure of the amount of data that can be sent and received at a time. While bandwidth is traditionally expressed in bits per second (bps), modern network links with greater capacity are often measured in megabits or gigabits per second. For example, having 5 Mbps bandwidth means you can receive up to 5 megabits of data per second.

The more bandwidth a connection has, the more data it can send or receive at a given time. Contrary to a common belief, bandwidth does not increase the connection’s speed; it only makes the network seem faster. Increased bandwidth does not mean increasing the transmission speed of the data.

42 .

What are Private and Special IP addresses?

Private Address : For each class, there are specific IPs that are reserved specifically for private use only. This IP address cannot be used for devices on the Internet as they are non-routable.

IPv4 Class	Private IPv4 Start Address	Private IPv4 End Address
A	10.0.0.0	10.255.255.255
B	172.16.0.0	172.31.255.255
B	192.168.0.0	192.168.255.255

Special Address : IP Range from 127.0.0.1 to 127.255.255.255 are network testing addresses also known as loopback addresses are the special IP address.

43 .

Describe the OSI Reference Model.

Open System Interconnections (OSI) is a network architecture model based on the ISO standards. It is called the OSI model as it deals with connecting the systems that are open for communication with other systems.

The OSI model has seven layers. The principles used to arrive at the seven layers can be summarized briefly as below :

* Create a new layer if a different abstraction is needed.

* Each layer should have a well-defined function.

* The function of each layer is chosen based on internationally standardized protocols.

44 .

Define the different layers of the OSI Reference Model.

Here the 7 layers of the OSI reference model :

OSI Layers

Layer	Unit Exchanged	Description
Physical	Bit	It is concerned with transmitting raw bits over a communication channel. Chooses which type of transmission mode is to be selected for the transmission. The available transmission modes are Simplex, Half Duplex and Full Duplex.,
Data Link	Frame	The main task of this layer is to transform a raw transmission facility into a line that appears free of undetected transmission errors. It also allows detecting damaged packets using the CRC (Cyclic Redundancy Check) error-detecting, code. When more than one node is connected to a shared link, Data Link Layer protocols are required to determine which device has control over the link at a given time. It is implemented by protocols like CSMA/CD, CSMA/CA, ALOHA, and Token Passing.
Network	Packet	It controls the operation of the subnet. The network layer takes care of feedback messaging through ICMP messages.
Transport	TPDU - Transaction Protocol Data Unit	The basic functionality of this layer is to accept data from the above layers, split it up into smaller units if needed, pass these to the network layer, and ensure that all the pieces arrive correctly at the other end. The Transport Layer takes care of Segmentation and Reassembly.
Session	SPDU - Session Protocol Data Unit	The session layer allows users on different machines to establish sessions between them. Dialogue control is using the full-duplex link as half-duplex. It sends out dummy packets from the client to the server when the client is ideal.
Presentation	PPDU - Presentation Protocol Data Unit	The presentation layer is concerned with the syntax and semantics of the information transmitted. It translates a message from a common form to the encoded format which will be understood by the receiver.
Application	APDU - Application Protocol Data Unit	It contains a variety of protocols that are commonly needed by users. The application layer sends data of any size to the transport layer.

45 .

Define the 4 different layers of the TCP/IP Reference Model

Layer	Description
Link	Decides which links such as serial lines or classic Ethernet must be used to meet the needs of the connectionless internet layer.
Internet	The internet layer is the most important layer which holds the whole architecture together. It delivers the IP packets where they are supposed to be delivered.
Transport	Its functionality is almost the same as the OSI transport layer. It enables peer entities on the network to carry on a conversation.
Application	It contains all the higher-level protocols.

46 .

What are the HTTP and the HTTPS protocol?

HTTP is the HyperText Transfer Protocol which defines the set of rules and standards on how the information can be transmitted on the World Wide Web (WWW). It helps the web browsers and web servers for communication. It is a ‘stateless protocol’ where each command is independent with respect to the previous command. HTTP is an application layer protocol built upon the TCP. It uses port 80 by default.

HTTPS is the HyperText Transfer Protocol Secure or Secure HTTP. It is an advanced and secured version of HTTP. On top of HTTP, SSL/TLS protocol is used to provide security. It enables secure transactions by encrypting the communication and also helps identify network servers securely. It uses port 443 by default.

47 .

What is the SMTP protocol?

SMTP is the Simple Mail Transfer Protocol. SMTP sets the rule for communication between servers. This set of rules helps the software to transmit emails over the internet.

It supports both End-to-End and Store-and-Forward methods. It is in always-listening mode on port 25.
SMTP Protocol

48 .

What is DNS Forwarder?

A forwarder is used with DNS server when it receives DNS queries that cannot be resolved quickly. So it forwards those requests to external DNS servers for resolution.

A DNS server which is configured as a forwarder will behave differently than the DNS server which is not configured as a forwarder.

Following are the ways that the DNS server behaves when it is configured as a forwarder:

* When the DNS server receives the query, then it resolves the query by using a cache.

* If the DNS server is not able to resolve the query, then it forwards the query to another DNS server.

* If the forwarder is not available, then it will try to resolve the query by using root hint.

49 .

What is NIC?

* NIC stands for Network Interface Card. It is a peripheral card attached to the PC to connect to a network. Every NIC has its own MAC address that identifies the PC on the network.

* It provides a wireless connection to a local area network.

* NICs were mainly used in desktop computers.

50 .

What is the UDP Protocol?

UDP is the User Datagram Protocol and is based on Datagrams. Mainly, it is used for multicasting and broadcasting. Its functionality is almost the same as TCP/IP Protocol except for the three ways of handshaking and error checking. It uses a simple transmission without any hand-shaking which makes it less reliable.

51 .

Compare between TCP and UDP

TCP/IP	UDP
Connection-Oriented Protocol	Connectionless Protocol
More Reliable	Less Reliable
Slower Transmission	Faster Transmission
Packets order can be preserved or can be rearranged	Packets order is not fixed and packets are independent of each other
Uses three ways handshake model for connection	No handshake for establishing the connection
TCP packets are heavy-weight	UDP packets are light-weight
Offers error checking mechanism	No error checking mechanism
Protocols like HTTP, FTP, Telnet, SMTP, HTTPS, etc use TCP at the transport layer	Protocols like DNS, RIP, SNMP, RTP, BOOTP, TFTP, NIP, etc use UDP at the transport layer

52 .

What is the meaning of 10Base-T?

It is used to specify data transfer rate. In 10Base-T, 10 specify the data transfer rate, i.e., 10Mbps. The word Base specifies the baseband as opposed to broadband. T specifies the type of the cable which is a twisted pair.

53 .

What is NOS in computer networking?

* NOS stands for Network Operating System. It is specialized software which is used to provide network connectivity to a computer to make communication possible with other computers and connected devices.

* NOS is the software which allows the device to communicate, share files with other devices.

* The first network operating system was Novel NetWare released in 1983. Some other examples of NOS are Windows 2000, Windows XP, Linux, etc.

54 .

What is the difference between a hub and a switch?

Here is the major difference between Hub and switch :

Hub	Switch
A hub operates on the physical layer.	A switch operates on the data link layer.
Hubs perform frame flooding that can be unicast, multicast, or broadcast.	It performs broadcast, then the unicast and multicast as needed.
Just a singular domain of collision is present in a hub.	Varied ports have separate collision domains.
The transmission mode is Half-duplex	The transmission mode is Full duplex
Hubs operate as a Layer 1 device per the OSI model.	Network switches help you to operate at Layer 2 of the OSI model.
To connect a network of personal computers should be joined through a central hub.	Allow connecting multiple devices and ports.
Uses electrical signal orbits	Uses frame & packet
Does not offer Spanning-Tree	Multiple Spanning-Tree is possible
Collisions occur mostly in setups using hubs.	No collisions occur in a full-duplex switch.
Hub is a passive device	A switch is an active device
A network hub can’t store MAC addresses.	Switches use CAM (Content Accessible Memory) that can be accessed by ASIC (Application Specific Integrated Chips).
Not an intelligent device	Intelligent device
Its speed is up to 10 Mbps	10/100 Mbps, 1 Gbps, 10 Gbps
Does not use software	Has software for administration

55 .

What is the Differences between IPv4 and IPv6?

IPv4 and IPv6 are internet protocol version 4 and internet protocol version 6, IP version 6 is the new version of Internet Protocol, which is way better than IP version 4 in terms of complexity and efficiency.

Difference Between IPv4 and IPv6 :

IPv4	IPv6
IPv4 has a 32-bit address length	IPv6 has a 128-bit address length
It Supports Manual and DHCP address configuration	It supports Auto and renumbering address configuration
In IPv4 end to end, connection integrity is Unachievable	In IPv6 end to end, connection integrity is Achievable
It can generate 4.29×10⁹ address space	Address space of IPv6 is quite large it can produce 3.4×10³⁸ address space
The Security feature is dependent on application	IPSEC is an inbuilt security feature in the IPv6 protocol
Address representation of IPv4 is in decimal	Address Representation of IPv6 is in hexadecimal
Fragmentation performed by Sender and forwarding routers	In IPv6 fragmentation performed only by the sender
In IPv4 Packet flow identification is not available	In IPv6 packet flow identification are Available and uses the flow label field in the header
In IPv4 checksum field is available	In IPv6 checksum field is not available
It has broadcast Message Transmission Scheme	In IPv6 multicast and anycast message transmission scheme is available
In IPv4 Encryption and Authentication facility not provided	In IPv6 Encryption and Authentication are provided
IPv4 has a header of 20-60 bytes.	IPv6 has header of 40 bytes fixed

56 .

What is Socket in Networking?

A Socket is a software structure that allows for communication between two or more programs running on the same or different machines within a network node. It can be seen as the endpoint of two-way communication commonly used in client-server applications. A socket can be created by linking the IP number of a system with a software port number where IP number and port number are separated by a ‘:’.

57 .

What is Routing in Networking?

Routing is a process of selecting a path for traffic across one or more networks. Network routing protocols use metrics to determine the optimal path for data packet delivery. For example, in the case of packet-switching networks such as the internet, routing helps to determine the best paths for Internet Protocol (IP) packets to travel from source to their destination.

Routing is performed by layer 3 or network layer for the process of most efficient path determination.

It can be classified into three categories :

* Static routing

* Dynamic routing

* Default routing

58 .

What is a Switch in Networking?

A network switch is a hardware device that connects multiple devices (such as computers, printers, servers, etc.) to a network to facilitate the sharing of information and resources. The devices can communicate with each other and share information regardless of whether they are in the same building or not. The most common form of the network switch is the Ethernet switch.

Switches in networking work on either layer 2 of the OSI model or layer 3 or the network layer. Layer 2 switches forward data packets based on the destination MAC address, while layer 3 switches forward data based on the destination IP addresses. Some switches can perform both functions.

59 .

What is Host in Networking?

A host refers to a computer device (or server) that is linked with other devices connected within a network. The network hosts are assigned at least one network address configured manually by an administrator or automatically assigned by means of DHCP.

A network host commonly acts as a sever offering services, information resources, software applications, etc., to users or other hosts in the network. A host participating in networks that use an internet protocol suite has its unique IP address and is called an IP host. The IP host is responsible for storing data and transfer it to other machines or computers, called remote terminals.

60 .

What is the ICMP protocol?

ICMP is the Internet Control Message Protocol. It is a network layer protocol used for error handling. It is mainly used by network devices like routers for diagnosing the network connection issues and crucial for error reporting and testing if the data is reaching the preferred destination in time. It uses port 7 by default.

61 .

What is the MAC address and how is it related to NIC?

MAC address is the Media Access Control address. It is a 48-bit or 64-bit unique identifier of devices in the network. It is also called the physical address embedded with Network Interface Card (NIC) used at the Data Link Layer. NIC is a hardware component in the networking device using which a device can connect to the network.

62 .

What is the difference between the ipconfig and the ifconfig?

ipconfig	ifconfig
Internet Protocol Configuration	Interface Configuration
Command used in Microsoft operating systems to view and configure network interfaces	Command used in MAC, Linux, UNIX operating systems to view and configure network interfaces
Used to get the TCP/IP summary and allows to changes the DHCP and DNS settings

63 .

What are Unicasting, Anycasting, Multicasting and Broadcasting?

Unicasting : If the message is sent to a single node from the source then it is known as unicasting. This is commonly used in networks to establish a new connection.

Anycasting : If the message is sent to any of the nodes from the source then it is known as anycasting. It is mainly used to get the content from any of the servers in the Content Delivery System.

Multicasting : If the message is sent to a subset of nodes from the source then it is known as multicasting. Used to send the same data to multiple receivers.

Broadcasting : If the message is sent to all the nodes in a network from a source then it is known as broadcasting. DHCP and ARP in the local network use broadcasting.

64 .

What is RIP in Networking?

* RIP stands for Routing Information Protocol. It is accessed by the routers to send data from one network to another.

* RIP is a dynamic protocol which is used to find the best route from source to the destination over a network by using the hop count algorithm.

* Routers use this protocol to exchange the network topology information.

* This protocol can be used by small or medium-sized networks.

65 .

What is Sneakernet?

Sneakernet is a slang term that refers to the transfer of data and electronic files between computers through removable media (like hard drives, flash drives and optical disks), which are physically transported between computers and on foot. This method is used in lieu of a computer network file transfer.

66 .

What is a server farm?

A server farm is a set of many servers interconnected together and housed within the same physical facility. A server farm provides the combined computing power of many servers by simultaneously executing one or more applications or services. A server farm is generally a part of an enterprise data center or a component of a supercomputer. A server farm is also known as a server cluster or computer ranch.

67 .

What is Symmetric and Asymmetric Encryption?

Symmetric Key Encryption : Encryption is a process to change the form of any message in order to protect it from reading by anyone. In Symmetric-key encryption the message is encrypted by using a key and the same key is used to decrypt the message which makes it easy to use but less secure. It also requires a safe method to transfer the key from one party to another.

Asymmetric Key Encryption : Asymmetric Key Encryption is based on public and private key encryption techniques. It uses two different keys to encrypt and decrypt the message. It is more secure than the symmetric key encryption technique but is much slower. For more details please refer difference between symmetric and asymmetric encryption articles.

68 .

Define Digital Signatures?

As the name sounds are the new alternative to sign a document digitally. It ensures that the message is sent to the intended use without any tampering by any third party (attacker). In simple words, digital signatures are used to verify the authenticity of the message sent electronically.

or we can say that – A digital signature is a mathematical technique used to validate the authenticity and integrity of a message, software, or digital document.

69 .

What is Network Authorization?

Authorization provides capabilities to enforce policies on network resources after the user has gained access to the network resources through authentication. After the authentication is successful, authorization can be used to determine what resources is the user allowed to access and the operations that can be performed.

70 .

What is the difference between IPS and a firewall?

The Intrusion Prevention System(IPS) is also known as Intrusion Detection and Prevention System. It is a network security application that monitors network or system activities for malicious activity. The major functions of intrusion prevention systems are to identify malicious activity, collect information about this activity, report it and attempt to block or stop it. Intrusion prevention systems are contemplated as augmentation of Intrusion Detection Systems (IDS) because both IPS and IDS operate network traffic and system activities for malicious activity. IPS typically records information related to observed events, notifies security administrators of important observed events, and produces reports. Many IPS can also respond to a detected threat by attempting to prevent it from succeeding. They use various response techniques, which involve the IPS stopping the attack itself, changing the security environment, or changing the attack’s content.

A firewall is a network security device, either hardware or software-based, which monitors all incoming and outgoing traffic, and based on a defined set of security rules it accepts, rejects, or drops that specific traffic.

71 .

What is IP Spoofing?

IP Spoofing is essentially a technique used by hackers to gain unauthorized access to Computers. Concepts of IP Spoofing were initially discussed in academic circles as early as 1980.

IP Spoofing types of attacks had been known to Security experts on the theoretical level. It was primarily theoretical until Robert Morris discovered a security weakness in the TCP protocol known as sequence prediction. Occasionally IP spoofing is done to mask the origins of a Dos attack. In fact, Dos attacks often mask the actual IP addresses from where the attack has originated from.

72 .

What are the different types of network cables used in networking?

The different types of cables used in networks are :

* Unshielded Twisted Pair (UTP) Cable

* Shielded Twisted Pair (STP) Cable

* Cable Installation Guides

* Coaxial Cable

* Fibre Optic Cable

* Wireless LANs

73 .

Differentiate between 'Forward DNS lookup' and 'Reverse DNS lookup'?

Following are the major differences between a forward lookup and reverse lookup in DNS :

Forward DNS lookup	Reverse DNS lookup
Converts a human input or a domain name to an IP address	Converts an IP address into a domain name
Has a mapping between hostnames and IP addresses	Has a mapping that relates IP addresses to hostnames
Used for a website or other server access	Used for network troubleshooting
Utilizes different servers with different IP addresses	Resolves reverse lookup queries where a client requests a hostname by providing an IP address
Uses A Records (basic) to identify any IP address for a particular hostname	Uses DNS pointer record to identify a hostname for a given IP address

74 .

How does a Frame Relay Work?

Frame Relay supports the multiplexing of traffic from multiple connections over a shared physical link. It uses hardware components that include router frames, bridges, and switches to pack data into individual frame relay messages. Each connection uses a 10-bit Data Link Connection Identifier (DLCI) for unique channel addressing. There are two types of connections :

* Permanent Virtual Circuits (PVCs) for persistent connections are intended to be maintained for long periods even if data is not actively transferred.

* Switched Virtual Circuits (SVCs) for temporary connections that last only one session.

Frame Relay then places the data in a variable-size unit called a frame and leaves any necessary error correction (data retransmission) until the endpoints, speeding up the overall transmission of data.

75 .

What are the different features of Frame Relay?

The different features of Frame Relay are :

* Frame Relay is a connectionless service, which means that every data packet that passes over the network contains address information

* Frame Relay is a service that is provided with a variety of speeds from 56 Kbs to 25 Mbs. Although the speeds most used for the service are currently 56 Kbs and 1,544 Mbs

* The frames are of variable length and go up to 4,096 bytes

* Frame Relay is considered a broadband ISDN service

* It operates at high speed (1,544 Mbps to 44,376 Mbps).

* It operates only on the physical and data link layers. Therefore, it can be easily used on the Internet.

* It has a large frame size of 9000 bytes. Therefore, it can accommodate all local area network frame sizes.

* Frame Relay can only detect errors (at the data link layer). But there is no flow control or error control. It operates in the data link layer.

76 .

How to find the IP address of a website?

Finding the IP address of a website or a domain is not a tricky task and involves the below steps –

* Press the “Start” button on your computer

* Type in the program and file browser “cdm”

* Hit “Enter”

* The MS-DOS console will open, where you must type “nslookup freetimelearning.com”. Instead of “freetimelearning.com”, you must write the domain name of the page you want to consult

* Next, you will be able to see the IP address
How to Find Website IP

77 .

What is the difference between a Domain and a Workgroup?

In a computer network, different computers are organized in different methods and these methods are – Domains and Workgroups. Usually, computers which run on the home network belong to a Workgroup.

However, computers that are running on an office network or any workplace network belong to the Domain.

Their differences are as follows :

Workgroup	Domain
All computers are peers and no computer has control over another computer	Network admin uses one or more computer as a server and provide all accesses, security permission to all other computers in a network
In a Workgroup, each computer maintains their own database	The domain is a form of a computer network in which computers, printers, and user accounts are registered in a central database.
Each computer has their own authentication rule for every user account	It has centralized authentication servers which set the rule of authentication
Each computer has set of user account. If user has account on that computer then only user able to access the computer	If user has an account in a domain then user can login to any computer in a domain
Workgroup does not bind to any security permission or does not require any password	Domain user has to provide security credentials whenever they are accessing the domain network
Computer settings need to change manually for each computer in a Workgroup	In a domain, changes made in one computer automatically made same changes to all other computers in a network
All computers must be on same local area network	In a domain, computers can be on a different local network
In a Workgroup, there can be only 20 computers connected	In a domain, thousands of computers can be connected

78 .

What is ACL in Networking?

ACL is an acronym for Access Control Lists. It is a set of rules used to control the network traffic and reduce network attacks. ACL works as a network filter and can only be configured on devices with packet filtering capabilities such as routers. The primary purpose of using an ACL is to provide network security. It contains a set of conditions that are applied on an interface basis to determine whether to allow or deny network traffic entering or leaving a network interface. The best place to configure an ACL is on the edge router that acts as a gateway for all outside networks. There are four types of ACLs based on their usage –

* Standard ACL

* Extended ACL

* Dynamic ACL

* Reflexive ACL

79 .

What is Multiplexing in Networking?.

Multiplexing is a process of combining multiple data streams into one signal over a single medium. The hardware device used for multiplexing is known as a Multiplexer that combines the ‘n’ number of input signals into a single output signal. There are two main types of multiplexers – analog and digital. Analog multiplexing involves signals which are analog and are multiplexed according to their frequency and wavelength. When digital signals are multiplexed in the form of frames and packets, the process is called digital multiplexing. Multiplexing in networking allows effective utilisation of the bandwidth when multiple signals share one medium.

80 .

What is ISP in Networking?

ISP stands for Internet Service Provider. ISP refers to a company that provides internet access and services, including internet transit, web hosting, domain name registration and email services, to name a few. An ISP serves as a gateway to access everything available on the internet, usually for a fee.

There are three levels of ISP.

A Tier 1 ISP sits at the top of the internet access pyramid with access to all networks on the internet.

These ISPs then sell access to Tier 2 ISPs which further sell access directly to organisations and individuals.

ISPs are responsible for maintaining network infrastructure, routing network traffic and enabling users to establish internet connectivity.

81 .

What is VLSM in Networking?

VLSM stands for Variable Length Subnet Masking. It is a subnet design strategy that allows subnet masks to have variable sizes within the same network. In other words, it involves a process of subnetting a subnet.

VLSM enables network engineers to divide an IP address into different sized subnets and allocate it according to the network needs. This means that more than one mask is used for different subnets of a single class A, B, or C networks, thereby increasing the usability of subnets. The network administrator must use the relevant supporting routing protocol to use VLSM such as Intermediate System-to-Intermediate System (IS-IS), Routing Information Protocol v2 (RIPv2), Border Gateway Protocol (BGP), and Open Shortest Path First (OSPF).

82 .

What is STP in Networking?

Spanning Tree Protocol (STP) is a network protocol designed to build a loop-free topology in the network. It is a layer 2 protocol that prevents broadcasts storms on networks with redundant paths.

The standardised STP protocols are specified as IEEE 802.1D. STP runs on 802.1D-compliant bridges and switches to prevent loops in a network. The configuration of STP requires a well-planned network topology by the administrator. STP increases the reliability of the network exponentially by introducing redundancy that is as important as backups in case an active link within the network fails.

83 .

What is ATM in Networking?

ATM stands for Asynchronous Transfer Mode and is a switching technique used by telecommunication networks to encode data into small fixed-size packets called cells. These cells are ideal for Time-Division Multiplexing (TDM) and transmit them over a physical medium.

Each ATM cell is 53 bytes long with a 5-byte header and a 48-byte payload. Since all the data is encoded into identical cells, the transmission is simple and uniform. This reduces packet overload and ensures that mixed traffic is handled efficiently. ATM is the core protocol used for Synchronous Optical Network (SONET), Fiber Distributed Data Interface (FDDI) and other high-speed networks. ATM networks can easy to work with and are scalable both in size and speed.

84 .

Explain what is Denial of Service (DoS)?

Denial of Service (DoS) is a kind of attack that prevents a legitimate user from accessing data over a network by a hacker or an attacker. The attacker floods the server with unnecessary requests in order to overload the server thereby preventing the legitimate users from accessing its services.

85 .

What is the full form of ASCII?

ASCII stands for American Standard Code for Information Interchange. It is a character encoding standard used in the electronic communication field. The ASCII codes basically represent text.

86 .

What is CGMP(cisco group management protocol)?

CGMP is a simple protocol, the routers are the only devices that are producing CGMP messages. The switches only listen to these messages and act upon it. CGMP uses a well-known destination MAC address (0100.0cdd.dddd) for all its messages. When switches receive frames with this destination address, they flood it on all their interfaces which so all switches in the network will receive CGMP messages.

Within a CGMP message, the two most important items are:

* Group Destination Address (GDA)

* Unicast Source Address (USA)

The group destination address is the multicast group MAC address, the unicast source address is the MAC address of the host (receiver).

87 .

What is BGP in Networking?

BGP stands for Border Gateway Protocol and is classified as the routing protocol of the global internet network. Think of it as the postal service of the internet that finds the most efficient route to deliver the letter to its recipient. It facilitates data routing and reachability between autonomous systems (AS) on the internet using an arbitrary topology.

BGP also helps conserve network bandwidth, support network security and facilitate coordination among multiple BGPs within the autonomous system (AS). Using BGP gives you more control over route selection and route advertisement by continually calculating the best path. That is why BGP is the routing protocol of the internet.

88 .

What is RFC in Networking?

RFC stands for Request For Comments and is mainly used to develop standard network protocols. It is a technical document published by the Internet Engineering Task Force (IETF) that contains various networking protocols, procedures, applications and technologies.

Almost all network protocols on the internet are built using RFCs. The final version of the document is published and sequentially numbered, which then becomes the standard. All standard network protocols such as FTP, HTTP, TCP, UDP, IP, etc., are defined as RFCs which form the base for cross-platform network communication.

89 .

Explain Proxy Server and its function.

IP addresses are required for data transmission and are even used by DNS to route to the correct website. Without knowledge of the actual and correct IP address, it is not possible to identify the network's physical location. Proxy servers prevent unauthorized access of IP addresses and make the computer network virtually invisible to external users.

90 .

What is File Transfer Protocol (FTP)?

FTP means "File Transfer Protocol" and refers to a group of rules that govern how computers transfer files from one system to another over the internet. Businesses use FTP to send files between computers, while websites use FTP for the uploading and downloading of files from their website's servers.

FTP works by opening two connections that link the computers trying to communicate with each other. One connection is designated for the commands and replies that get sent between the two clients, and the other channel handles the transfer of data. During an FTP transmission, there are four commands used by the computers, servers, or proxy servers that are communicating. These are “send,” “get,” “change directory,” and “transfer.”

While transferring files, FTP uses three different modes: block, stream, and compressed. The stream mode enables FTP to manage information in a string of data without any boundaries between them. The block mode separates the data into blocks, and in the compress mode, FTP uses an algorithm called the Lempel-Ziv to compress the data.

91 .

How Many Types of FTP Are There?

While FTP can be used to accomplish several kinds of tasks, there are three primary categories of FTPs.

FTP Plain : FTP Plain refers to normal FTP without encryption. By default, it uses port 21, and it is supported by the majority of web browsers.

FTPS : FTPS refers to FTP Secure or FTP secure sockets layer (SSL) because this kind of FTP server uses SSL encryption, which is slightly different than traditional FTP. The primary difference is the security that comes with FTPS, which was the first type of encrypted FTP invented.

FTPES : The “E” in FTPES means “explicit,” making the acronym stand for File Transfer Protocol over explicit transport layer security (TLS)/SSL. This type of FTP begins like regular FTP, using port 21, but then special commands upgrade it to a TLS/SSL-encrypted transmission. Because it tends to work well with firewalls, some prefer to use FTPES over FTPS.

How to Use FTP

The three most common ways of using FTP include:

Via a web browser: With a web browser, you do not need any special software or a client to download files from servers that provide for FTP sites.

A General User Interface (GUI) FTP client: These third-party applications enable users to connect and then send files over FTP.

Command-line FTP : Major operating systems come equipped with FTP client capabilities as a command line.

92 .

What is an anonymous FTP?

Anonymous FTP allows users to access public data. The user need not identify himself to the server, and the login is anonymous. So, while using anonymous FTP, you are required to add 'anonymous' in place of the user id. Anonymous FTPs effectively distribute large files to many people without giving vast numbers of password and username combinations.

93 .

What is the difference between FTP vs. SFTP?

FTP stands for File Transfer Protocol, while SFTP refers to Secure Shell (SSH) File Transfer Protocol. This gives you file transfers that are secured via SSH, which provides full access to shell accounts. A shell account is one that sits on a remote server.

FTP is different from SFTP in that it does not give users a secure channel for transferring files. Also, FTP makes use of two channels for transferring data, but SFTP only uses a single channel. The inbound connections that each protocol uses are different as well. FTP defaults to port 21, but SFTP allows inbound communication on port 22.

The manner in which data is transferred is also significantly different. SFTP uses a tunneling method to transfer data. With the benefit of additional security, FTP, which is less secure, uses direct transfer.

94 .

What is the difference between Bluetooth and wifi?

S.NO	Bluetooth	Wifi
1.	Bluetooth has no full form.	While wifi stands for Wireless Fidelity.
2.	It requires bluetooth adapter on all devices for connectivity.	Whereas it requires a wireless adapter Bluetooth for all devices and a wireless router for connectivity.
3.	Bluetooth consumes low power.	while it consumes high power.
4.	The security of BlueTooth is less in comparison to the number of wifi.	While it provides better security than BlueTooth.
5.	Bluetooth is less flexible means these limited users are supported.	Whereas wifi supports large amount of users.
6.	The radio signal range of BlueTooth is ten meters.	Whereas in wifi this range is a hundred meters.
7.	Bluetooth requires low bandwidth.	While it requires high bandwidth.

95 .

What is a reverse proxy?

Reverse Proxy Server : The job of a reverse proxy server to listen to the request made by the client and redirect to the particular web server which is present on different servers. This is also used to restrict the access of the clients to the confidential data residing on the particular servers.

96 .

Define piggybacking?

A technique called piggybacking is used to improve the efficiency of the bidirectional protocols. When a frame is carrying data from A to B, it can also carry control information about arrived (or lost) frames from B; when a frame is carrying data from B to A, it can also carry control information about the arrived (or lost) frames from A.

97 .

What are the advantages and disadvantages of piggybacking?

The major advantage of piggybacking is better use of available channel bandwidth.

The major disadvantage of piggybacking is additional complexity and if the data link layer waits too long before transmitting the acknowledgment, then re-transmission of the frame would take place.

98 .

Why do we need the pop3 protocol for e-mail?

The Post Office Protocol (POP3) is that the most widely used protocol and is being supported by most email clients. It provides a convenient and standard way for users to access mailboxes and download messages. An important advantage of this is that the mail messages get delivered to the client’s PC and they can be read with or without accessing the web.

99 .

What is a Hamming code?

Hamming code is a liner code that is useful for error detection up to two immediate bit errors. It is capable of single-bit errors.

In Hamming code, the source encodes the message by adding redundant bits in the message. These redundant bits are mostly inserted and generated at certain positions in the message to accomplish the error detection and correction process.

100 .

What is the Application of Hamming code?

Here are some common applications of using Hemming code:

* Satellites

* Computer Memory

* Modems

* PlasmaCAM

* Open connectors

* Shielding wire

* Embedded Processor

101 .

What are the benefits of the Hamming code?

Here, are important benefits of Hamming code

* The Hamming code method is effective on networks where the data streams are given for the single-bit errors.

* Hamming code not only provides the detection of a bit error but also helps you to indent bit containing error so that it can be corrected.

* The ease of use of hamming codes makes it suitable for use in computer memory and single-error correction.

102 .

What are the types of MAC Addresses?

Here are the important types of MAC addresses:

Universally Administered AddressUAA(Universally Administered Address) is the most used type of MAC address. It is given to the network adapter at the time of manufacturing.

Locally Administered AddressLAA (Locally Administered Address) is an address that changes the MAC address of the adapter. You may assign this address to a device used by network administrator.

103 .

What are the important differences between MAC address and IP address?

Here, are some difference between MAC and IP address :

MAC	IP address
The MAC address stands for Media Access Control Address.	IP address stands for Internet Protocol Address.
It consists of a 48-bit address.	It consists of a 32-bit address.
MAC address works at the link layer of the OSI model.	IP address works at the network layer of OSI model.
It is referred to as a physical address.	It is referred to as a logical address.
You can retrieve the MAC address of any device using ARP protocol.	You can retrieve the MAC address of any device RARP protocol.
Classes are not used in MAC address.	In IP, IPv4 uses A, B, C, D, and E classes.

104 .

What is the difference between the Internet, Intranet, and Extranet?

The terminologies Internet, Intranet, and Extranet are used to define how the applications in the network can be accessed. They use similar TCP/IP technology but differ in terms of access levels for each user inside the network and outside the network.

Internet : Applications are accessed by anyone from any location using the web.

Intranet : It allows limited access to users in the same organization.

Extranet : External users are allowed or provided with access to use the network application of the organization.

105 .

What Is a Modem in Computer Networking?

A modem converts data to a signal so it can be easily sent and received over a phone line, cable, or satellite connection. For transmission over an analog telephone line—which was once the most popular way to access the internet—the modem converts data between analog and digital formats in real time for two-way network communication. In the case of the high-speed digital modems popular today, the signal is much simpler and doesn't require the analog-to-digital conversion.

Modem

106 .

What is SNMP in Networking?

SNMP stands for Simple Network Management Protocol. It is a network protocol used for collecting organizing and exchanging information between network devices. SNMP is widely used in network management for configuring network devices like switches, hubs, routers, printers, servers.

SNMP consists of the below components :

* SNMP Manager

* Managed device

* SNMP Agent

* Management Information Base (MIB)