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Networking Interview Questions
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,.
Networking
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.
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
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.
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.

What is LAN

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.
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.
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
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
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.
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.