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Cloud Computing Interview Questions
A cloud is a combination of networks ,hardware, services, storage, and interfaces that helps in delivering computing as a service. It has three users :
 
* End users
* Business management users
* cloud service provider
Cloud computing is an internet based new age computer technology. Cloud computing is an on-demand availability of computer system resources that uses the clouds to provide the services when the user needs them and helps the users avail of a more extensive network of global web servers. 
 
This is because it’s seen the fastest adoption into the mainstream than the other technology within the domain. This adoption has been fueled mainly by the ever-increasing number of smartphones and mobile devices which may access the web.
 
Cloud computing isn’t just for organizations and businesses; it’s also useful for the standard person. It enables us to run software programs without installing them on our computers; it enables us to store and access our multimedia content online. Pooled computing resources available through cloud computing are proven to supply tremendous benefits to business organizations.
 
Cloud computing examples are : 
 
Cybersecurity : Forcepoint
Big Data Analysis : Civis Analytics
Platform-as-a-Service (SaaS) : AWS
Software-as-a-Service (SaaS)
:
Salesforce
Infrastructure-as-a-Service (SaaS) : DigitalOcean
File Sharing + Data Storage : Dropbox
Data Governance : Carbonite
 
The following are some of the key features of cloud computing :
 
Agility : Helps in quick and inexpensive re-provisioning of resources.
Location Independence : This means that the resources can be accessed from everywhere.
Multi-Tenancy : The resources are shared amongst a large group of users.
Reliability : Resources and computation can be dependable for accessibility.
Scalability : Dynamic provisioning of data helps in scaling.
Cloud delivery models are models that represent the computing environments. These are as follows:
 
Infrastructure as a Service (IaaS) : Infrastructure as a Service (IaaS) is the delivery of services, including an operating system, storage, networking, and various utility software elements, on a request basis. 

Platform as a Service (PaaS) : Platform as a Service (PaaS) is a mechanism for combining Infrastructure as a Service with an abstracted set of middleware services, software development, and deployment tools. These allow the organization to have a consistent way to create and deploy applications on a cloud or on-premises environment.

Software as a Service (SaaS) : Software as a Service (SaaS) is a business application created and hosted by a provider in a multi-tenant model.
 
Function as a Service (FaaS) : Function as a Service (FaaS) gives a platform for customers to build, manage and run app functionalities without the difficulty of maintaining infrastructure. One can thus achieve a "serverless" architecture.
There are two primary deployment models of the cloud : Public and Private
 
Public  Cloud : The set of hardware, networking, storage, services, applications, and interfaces owned and operated by a third party for use by other companies or individuals is the public cloud. These commercial providers create a highly scalable data center that hides the details of the underlying infrastructure from the consumer. Public clouds are viable because they offer many options for computing, storage, and a rich set of other services.

Private Cloud : The set of hardware, networking, storage, services, applications, and interfaces owned and operated by an organization for the use of its employees, partners, or customers is the private cloud. This can be created and managed by a third party for the exclusive use of one enterprise. The private cloud is a highly controlled environment not open for public consumption. Thus, it sits behind a firewall.

Hybrid Cloud : Most companies use a combination of private computing resources and public services, called the hybrid cloud environment. 

Multi-Cloud : Some companies, in addition, also use a variety of public cloud services to support the different developer and business units – called a multi-cloud environment.
Following are the different layers that are used by cloud architecture :
 
* Walrus
* CLC or Cloud Controller
* Cluster Controller
* SC or Storage Controller
* NC or Node Controller
The platforms that are used for large scale cloud computing are
 
* Apache Hadoop
* MapReduce
Cloud Computing offers 3 types of security aspects, which are :
 
* Identity Management : Authorizes application services
* Access Control : Controls the access of users entering the cloud environment
* Authentication & Authorization : Allows only authorized and authenticated users to access the data and applications

Efficiency; Efficiency in business operations is achieved within the following ways through the utilization of cloud computing : 
 
Accessibility; Cloud computing facilitates the access of applications and data from any location worldwide and any device with an online connection. 
 
Cost savings; Cloud computing over businesses with scalable computing resources hence saving them on the worth of acquiring and maintaining them. These resources are purchased on a pay-as-you-go basis which suggests businesses pay just for the resources they use. This has proven to be less expensive than acquiring the resources on their own. 
 
Security; Cloud providers especially those private cloud services which have strived to implement the simplest security standards and procedures to guard client’s data saved within the cloud. 
 
Disaster recovery; Cloud computing is the foremost efficient means for little, medium and even large enterprises to backup and restore their data and applications in a fast and reliable way. 
 
Flexibility and Increased collaboration; with the capabilities of cloud computing, individuals from different places can collaborate in business projects without necessarily having to satisfy. 

The various cloud data types include – emails, text, Boolean, decimal, locale, number, date, images, contacts, etc. As we know that data is increasing day by day so it is needed for new data types to store these new data. For example, if you want to store video then you need a new data type.
Even though this might sound like a fundamental question, this was asked in one of the interviews. (source- Quora)
Now, you must use simple words while answering this question. Use of technical terms is not advised.

In cloud computing, ‘cloud’ refers to the internet, metaphorically. So cloud computing is a method where the internet acts as the fuel to computing services. You can now use the word- Internet-based computing. 
System Integrators emerged into the scene in 2006. System integration is the practice of bringing together components of a system into a whole and making sure that the system performs smoothly.

A person or a company that specializes in system integration is called a system integrator.
* A private cloud delivers similar advantages to public cloud-like scalability and self-service. In the private cloud, this is done by using a proprietary architecture. Private clouds focus on the needs and demands of a single organization.

* As a result, the private cloud is best for businesses with dynamic or unpredictable computing needs that require direct control over their environments. Security, governance, and regulation are best suited for private cloud services.

* Private clouds are used to keep the strategic operations and others secure. It is a complete platform that is fully functional and can be owned, operated and restricted to only an organization or an industry. Nowadays, most organizations have moved to private clouds due to security concerns. Virtual private cloud is being used that operate by a hosting company.
* Be it a public or private cloud, the primary objective is to deliver services using the internet. Unlike a private cloud, public cloud services are third-party applications that can be used by anybody who wants to access them. The service may be free or be sold on demand.

* Public clouds are open to people for use and deployment. For example Google and Amazon etc. The public clouds focus on a few layers like cloud application, providing infrastructure, and providing platform markets.
* A hybrid cloud is a cloud computing environment where we can use the services available to us locally, use third-party private services, and public services as well to meet the demand. By allowing workloads to move between private and public clouds as computing needs and costs change, hybrid cloud gives businesses greater flexibility and more data deployment options.

* Hybrid clouds are a combination of public clouds and private clouds. It is preferred over both clouds because it applies the most robust approach to implement cloud architecture. It includes the functionalities and features of both worlds. It allows organizations to create their cloud and allow them to give control over someone else as well.
* Cloud Computing is when you store your files and folders in a “cloud” on the Internet, this will give you the flexibility to access all your files and folders wherever you are in the world– but you do need a physical device with Internet access to access it.

* Mobile computing is taking a physical device with you. This could be a laptop or mobile phone or some device. Mobile computing and cloud computing are somewhat analogous. Mobile computing uses the concept of cloud computing. Cloud computing provides the users with the data which they require while in mobile computing, applications run on the remote server and give the user access for storage and managing the data.
Scalability is a characteristic of cloud computing that is used to handle the increasing workload by increasing in proportion amount of resource capacity. By the use of scalability, the architecture provides on-demand resources if the traffic is raising the requirement.
 
Whereas, Elasticity is a characteristic that provides the concept of commissioning and decommissioning of a large amount of resource capacity dynamically. It is measured by the speed at which the resources are on-demand and the usage of the resources.
It is one of the most commonly asked cloud computing interview questions. Some of the biggest cloud providers and databases are :
 
* Amazon Web Services(AWS)
* SAP
* EnterpriseDB
* Garantia Data
* Cloud SQL by Google
* Azure by Microsoft
* Rackspace
* Google bigtable
* Amazon simpleDB
* Cloud-based SQL
EUCALYPTUS” stands for Elastic Utility Computing Architecture For Linking Your Programs To Useful Systems.
Eucalyptus” is an open source software infrastructure in cloud computing, which is used to implement clusters in cloud computing platform. It is used to build public, hybrid and private clouds. It has the ability to produce your own data center into a private cloud and allows you to use its functionality to many other organizations.
The requirement of virtualization platform in implementing cloud is to
 
* Manage the service level policies
* Cloud Operating System
* Virtualization platforms helps to keep the backend level and user level concepts different from each other
API’s ( Application Programming Interface) is very useful in cloud platforms
 
* It eliminates the need to write the fully fledged programs
* It provides the instructions to make communication between one or more applications
* It allows easy creation of applications and link the cloud services with other systems
Cloud service is used to build cloud applications using the server in a network through internet.  It provides the facility of using the cloud application without installing it on the computer. It also reduces the maintenance and support of the application which are developed using cloud service.
Following are the main advantages of cloud services :

Cost-saving : It helps in the utilization of investment in the corporate sector. So, it is cost saving.

Scalable and Robust : It helps in developing scalable and robust applications. Previously, the scaling took months, but now, scaling takes less time.

Time-saving : It helps in saving time regarding deployment and maintenance.
The Windows Azure Operating System is used for cloud services to be run on the Windows Azure Platform. Azure is preferred as it includes the essential features for hosting all the services in the cloud. You also get a runtime environment that consists of a Web Server, Primary Storage, Management services, load balancers among others. The Windows Azure system provides the fabric for the development and testing of services before their deployment on the Windows Azure in the cloud.
It is a virtual machine screen that can logically manage resources for virtual machines. It allocates, partition, isolate or change with the program given as virtualization hypervisor. Hardware hypervisor allows having multiple guest Operating Systems running on a single host system at the same time.
 
It is also known as Virtual Machine Manager. There are two types of hypervisors as defined below :
 
Type 1 : The guest Vm runs directly over the host hardware, e.g. Citrix XenServer, VMware ESXI.
 
Type 2 : The guest Vm runs over hardware through a host OS, e.g. oracle virtual box, Vmware Player.
 
Type 1 Hypervisor works much better than Type 2 because there is no underlying middleware and thus making the best environment for critical applications and workloads. To compare the performance metrics we need to determine the CPU overhead, amount of maximum host and guest memory and support for virtual processors.
Considering the various benefits of cloud computing to organizations, a good case is that cloud computing is increasingly becoming the new normal. Cloud computing helps society to deal with future problems like managing big data, cyber-security and internal control.
 
In addition to the present, emerging technologies like AI, distributed ledger technology, and lots of other capabilities are getting available as services through cloud computing. Consequently, these technologies to be adaptable to varied platforms like mobile devices hence increasing their use.
 
Innovations supported cloud computing like cloud automation and therefore the Industry cloud also is being developed to integrate cloud computing into more specific industrial activities which can make various operations even more streamlined. The verdict for cloud computing is that it’s a transitional technology that has helped organizations in several jurisdictions to deliver their products and services in a better way than before.
Load balancing helps to :
 
* Increase utilization and output
* Lower latency
* Cut back response time
* Avoid system overload
Virtualization in cloud computing is very much required to :
 
* Decouple hardware from software
* Save the cost for components like hardware and servers
* Store the data in the virtual server
* Reduce the wastage, electricity bills, and maintenance costs
Different types of virtualization in cloud computing are :

Virtualisation provides an abstraction between the back end and user programs. It enables creating an environment where multiple software can use the same hardware. Virtualisation also manages the service level policies. Following are a few types of virtualisation seen in Cloud Computing.
 
Server Virtualization partitions a server into multiple serves so it can distribute incoming traffic among them. The use case is load balancing.

Software Virtualization is a technique that allows one computer server to work with more than one virtual system. The primary function of software Virtualization is to develop virtual Software and make the work easier. It produces a simple virtual machine on which the system can work as regularly.

Hardware Virtualization is where Virtual Machine Manage installs on the hardware. It provides easy access and monitors of resources like memory, processors, etc.
 
Storage Virtualisation takes multiple Network storage devices and clubs them into one single group, providing abstraction. The group is easier to maintain when compared to numerous devices inside it.
 
Operating System Virtualisation is when multiple OSs run on the same hardware. It is possible by installing the VMM onto the host OS instead of the hardware.
 
Desktop Virtualisation allows remote access to workstations across global data centres, managed over the internet.
 
Application Virtualisation ensures applications that run on one operating system can run on other operating systems as well. It creates an abstraction between the OS and the application.
 
Network virtualization is the transformation of a network that was once hardware-dependent into a network that is software-based. Like all forms of IT virtualization, the basic goal of network virtualization is to introduce a layer of abstraction between physical hardware and the applications and services that use that hardware.
Following are the essential things that must be followed before going for the cloud computing platform :
 
* Uptime
* Loss of data
* Data storage
* Compliance
* Business continuity
* Data integrity in cloud computing
Following are the components needed in cloud architecture :
 
* Cloud Ingress
* Cloud provided services
* Cloud storage services
* Processor Speed
* Intra-cloud communications
Buffer is used to build the system more accurately against the burst of traffic. It helps to align different components. The components are equivalent because it is managed by buffers and make them work at the same speed to provide faster services.
The strategy dictates to not rely completely on a single cloud service provider and distribute the traffic among multiple cloud service providers. Different functionalities can be leveraged from different cloud providers, thus reducing work from one particular provider. This helps in increasing independence and lowers the risk of failure in the case the provider faults or there occurs a traffic overload.

Multi-cloud comes in use as a design to govern from a singular access point ( portal )over the multiple cloud architecture. It can be as simple as a portal to overlook all the clouds and their functionality.
Cloud VPN(Virtual Private Network) helps companies transition their VPN services to the cloud. There are two types of VPN services that are available - Remote Access and Site to Site connection.
 
A VPN appliance is installed on-site in the company network in a Site-to-Site connection. This appliance connects to a virtual VPN endpoint in the cloud. The VPN results in a  tunnel between the cloud and the enterprise. This connection doesn’t need the public IP address and acts similar to a physical connection. 
 
Remote Access enables users to connect to machines located elsewhere globally. For example - VPNaaS
 
In the connection logic, users install VPN software on their machines and connect to cloud VPN. The cloud VPN forwards the connection to the concerned SaaS application.
The Recovery Time Objective is the maximum time a company has accepted to wait for recovery when a system fails in the cloud. This contract is between the cloud provider and the client.
 
A Recovery Point Object is the maximum amount of data loss that the organisation can accept in its contract. The data loss is measured in time. 
VPC manages storage and compute resources for organisations by providing a layer of isolation and abstraction. 
 
The architecture for VPC with public and private subnets is as follows : 
 
Creating a new VPC instance :
 
A VPC comes by default with these components :
 
* Route table
* Network ACL
* Security Groups
Data can be encrypted in S3 using SSE-S3, SSE-C, SSE-KMS.
 
SSE-S3 provides the solution S3 oversees Key management and protection using multiple layers of security. 
 
SSE-C lets S3 perform encryption and decryption of data and control the key used for encryption. Key management and storage are implementation-dependent and not provided by AWS.
 
SSE-KMS uses the Amazon Key Management service to store the keys used in encryption. KMS also provides an additional layer of security by keeping master keys. Special permission is needed to be able to use the master key.
Memory-Optimized Instances : They provide fast performance for applications that process Bigdata in memory. Memory Optimised instance includes support for enhanced networking, up to 25gbps of Network Bandwidth. They come packaged with EBS installed and optimised.
 
Use cases are in-memory caches and open-source databases. 
 
Compute Optimised Instances : Compute Optimised instances provide high-performance computing resources and fast batch-processing. They are used ideally for media transcoding, gaming servers, ad-server engines. Compute Optimised Instances use the AWS Nitro system, which combines dedicated hardware and lightweight hypervisors. Just like Memory-optimized, Compute Optimised Instances come with optimised EBS as well.
 
Accelerated Computing Instances : These Instances use co-processors and hardware accelerators to improve upon the performance. They get used in graphics processing, floating-point calculations, data pattern matching. Accelerated Computing Instances use extra hardware power to combat software limitations and latency. These also support the Elastic Fabric Adapter (EFA)
 
Storage Optimised Instances : Storage Optimised instances are ideal for workloads that need high sequential read and write. These instances use their local storage to store data.
 
Storage optimised instances provide low latency and high-speed random I/O operations. They get used in NoSQL databases like Redis, MongoDB, data warehousing.
 
General Purpose instances provide a mixture of computing, memory, and networking resources. General Purpose Instance find their use in applications that consume multiple resources in equal proportions, for example, web servers, code repositories.
Application Load Balancer (ALB) : ALB allows routing based on port numbers. It can also route requests to Lambda, and it can direct requests to many ports on the target. Application Load Balancer supports only layer 7 - HTTP/2 and Web Sockets. It can return primary responses on its own so the server can be set free of replying to redundant requests. ALB find use in Microservices and application
 
Network Load Balancer (NLB) : Network Load Balancer supports Layer 4 that is TCP and UDP. It is faster and high-performance since it is lower in the OSI model. It uses static IPs and can also be assigned elastic IPs. An example would be real-time data streaming or video streaming.
 
Classic Load Balancer (CLB) or Elastic Load Balancer (ELB version1) : ELB is the oldest Load balancer and the only one which offers application-specific sticky session cookies. It works both on Layer 7 and Layer 4. ELB also supports EC2-Classic.
Amazon AWS provides Shields for security against attacks. AWS Shields uses two tiers of security- Standard and Advanced. 
 
Standard AWS Shield, which comes by default with AWS, can be used as a first-measure security gate. It protects network and transport layers.
 
Subsequently, one can also subscribe to Shield Advanced for another layer of added security. The AWS Advanced Shield provides integration with AWS Web Application Firewall (WAF). AWS WAF provides custom rules to filter out traffic with threat signatures.
 
Web Application Firewall provides three main actions : allow all requests for a rule, block all requests, and count all requests for a new policy.
Aurora is the database engine that gives reliability and speed at par with industry-standard databases. It backs up data in AWS S3 in real-time without any performance impact. It backs up storage in a routine fashion without the hassle of Database administrators interfering.
 
RDS (Amazon Relational Database System) is the traditional relational database that provides scalability and cost-effective solutions for storing data. It supports six database engines, i.e. MySQL, Postgres, Amazon Aurora, MariaDB, Microsoft SQL Server, Oracle.
Google Compute Engine is an IAAS product that provides easy to run and flexible virtual machines with Windows and Linux as host OS. It runs on local storage, KVM, or durable storage.
 
Google Compute Engine integrates with other GCP technologies (e.g., BigQuery, Google Cloud Storage)  to make more complex systems.
 
While Google Compute App is a PaaS offering under Google Cloud Platform, it provides the platform for customers to run their services or applications. It offers Infrastructure and environment both to the client, so it forms the larger umbrella with IaaS under it.
* XML API and JSON API, used predominantly.
* Google cloud platform console.
* Google storage client libraries.
* gsutil command-line tool.
The hybrid cloud term is supposed to be integrating public and private clouds.
 
Hybrid IT is what results when hybrid cloud efforts in organizations become more of advanced virtualization and automation environments with various features. And there haven’t been a lot of success stories of organizations being able to really build and maintain real hybrid clouds.
 
They’ve done some things with OpenStack, but, for the most part, private cloud-inspired environments powered by VMware dominate. Therefore, a substitute term — hybrid IT — actually better describes the bulk of hybrid scenarios. This does not, however, change the need for clarity in terminology.
 
The hybrid cloud must involve some combination of cloud styles (private, public, community), but physical location is not a definitive aspect of the style. The bottom line is that most users of the hybrid cloud term have really meant hybrid IT thus far.
The distributed cloud may be defined as the distribution of public cloud services to different physical locations. In contrast, operation, governance, updates, and the evolution of the services are the responsibility of the originating public cloud provider.
 
Distributed cloud computing is a style of cloud computing where the location of the cloud services is a critical component of the model. Historically, the location has not been relevant to cloud computing definitions, although issues related to it are essential in many situations. While many people claim that a private cloud or hybrid cloud requires on-premises computing, this is a misconception.
 
A private cloud can be done in a hosted data center or, more often, in virtual individual cloud instances, which are not on-premises. Likewise, the hybrid cloud does not require that the individual components of the hybrid are in any specific location. However, with the advent of distributed cloud, location formally enters the definition of a style of cloud services.
 
Distributed cloud supports the tethered and untethered operation of like-for-like cloud services from the public cloud “distributed” out to specific and varied physical locations. This enables an essential characteristic of distributed cloud operation — low-latency compute where the to compute operations for the cloud services are closer to those who need the capabilities. This can result in major upgrades in performance and reduce the risk of global network-related outages.
Cloud Controller
 
* Automatically creates virtual machines and controllers
* Deploys applications
* Connects to services
* Automatically scales up and down


Storage Services
 
* Object
* NoSQL
* Relational
* Block storage


Applications Stored in Storage Services
 
* Simple-to-scale applications
* Easier recovery from failure
Microservices help create apps that consist of codes that are independent of one another and the platform they were developed on.  Microservices are important in the cloud because of the following reasons :
 
* Each of them is built for a particular purpose. This makes app development simpler.
* They make changes easier and quicker. 
* Their scalability makes it easier to adapt the service as needed.
Edge computing is a part of the distributed computing structure. It brings companies closer to the sources of data. This benefits businesses by giving them better insights, good response time and better bandwidth.
Cloud Computing consists of different data centers as follows :
 
Containerized data centers : Containerized data centers are the packages that contain a consistent set of servers, network components, and storage delivered to large warehouse kind of facilities. Here, each deployment is relatively unique.

Low-density data centers : Containerized data centers promote heavy density which in turn causes much heat and significant engineering troubles. Low-density data centers are the solution to this problem. Here, the equipment is established far apart so that it cools down the generated heat.
Cloud computing refers to an honest space of knowledge technology (IT) that touches on the following areas: We can begin with a basic assumption: you don’t want a degree or a computing or pc engineering degree to search out cloud computing.
 
The aforesaid points highlight the advantages of exploiting cloud technology and so the following discussion can define the potential cons of Cloud Computing.
 
Vulnerability to attacks : Storing information within the cloud might cause serious challenges {of information of knowledge} thievery since within the cloud each data of a corporation is online. Security breach are some things that even the only organizations have suffered from and it’s a potential risk inside the cloud conjointly .though advanced security measures are deployed on the cloud, still storing confidential information inside the cloud are usually a risky affair.
 
Network property dependency : Cloud Computing is entirely enthusiastic about the net. This direct tie-up with the net means that an organization should have reliable and consistent web service conjointly as a fast affiliation and information measure to reap the advantages
 
Downtime : the period of time is taken into consideration along with the foremost vital potential downsides of exploitation Cloud Computing. The cloud suppliers might typically face technical outages which might happen to owe to varied reasons, like loss of power, low web property, information centres going out of service for maintenance, etc. which could cause a brief-lived period of time inside the cloud service.
 
Vendor lock-in : once in need to migrate from one cloud platform to a distinct, an organization would possibly face some serious challenges thanks to the variations between seller platforms. Hosting and running the applications of this cloud platform on another platform might cause support problems, configuration complexities, and additional expenses.
 
The corporate information might boot be left liable to security attacks due to compromises that can are created throughout migrations.
 
Limited management : Cloud customers might face restricted control over their deployments. Cloud services run on remote servers that are utterly closely held and managed by service suppliers, which makes it arduous for businesses to possess the extent of management.
* Security : Actually, data is stored in the cloud, so security may be an issue for some users. However, cloud computing is not more secure than in-house deployment.
 
* Latency issue : Since data and applications are stored in the cloud at a variable distance from the end-user, there is a possibility that there may be greater latency when interacting with the application compared to local deployment. Therefore, the SaaS model is not suitable for applications whose demand response time is in milliseconds.
 
* Total Dependency on the Internet : Without an internet connection, most SaaS applications are not usable.
 
* Switching between SaaS vendors is difficult : Switching SaaS vendors involves the difficult and slow task of transferring the very large data files over the internet and then converting and importing them into another SaaS also.
* Shared Infrastructure.
* IaaS gives shared users to share the same physical infrastructure.
* Web Access to the resources.
* IaaS allows IT users to access resources over the internet.
* On demand as per usage model.
* Iaas providers provide services only as client’s pay as you go model.
* Business model focus.
* Iaas Providers give business core organization focus rather than IT infra.
* Update versions of Software.
* There is scalability of services provided as there is no worrisome of software upgrade and troubleshoot the issues related to IT infrastructure.
* Security
* Security is the main concern in IaaS as it is not 100percent sure.
* Maintenance and up gradation
* Although IaaS providers maintain the software but not for all.
* Interoperability issues
* It is difficult to migrate Virtual Machine form one IaaS provider to another, so customers experience problem related to vendor lock.
* Main Iaas Cloud Service providers are Amazon Web Services, Microsoft Azure, and Google Cloud Platform etc.
Vendor lock-in : Development according to the particular vendor can be easy but migration to another cloud provider can be a problem.
 
Data privacy : Corporate data, whether can be important or not, will always be private. It should always be an insecure environment.
 
Synchronization of system applications : We have integrated many applications with local and on the cloud, so there is the problem of increased complexity when mixing local data with cloud data.
 
Most PaaS cloud providers are Salesforce, Windows Azure, and Google App Engine etc.
IaaS layer is to blame for user authentication in cloud computing. IaaS layer is to blame for user authentication in cloud computing. IaaS could be a user based mostly system that’s to blame for authentication services like accessing, managing, and watching.
It’s the distribution of workloads across multiple computing resources. It reduces prices related to management systems and will increase the handiness of resources. It has an advantage over different load equalization in that it will transfer masses to servers globally as hostile distributing it across native servers. In the event of an area server outage, cloud equalization delivers users to the nearest regional server
Cloud storage device mechanisms provide common levels of data storage, such as :
 
Files : These are collections of data that are grouped into files that are located in folders.

Blocks : A block is the smallest unit of data that is individually accessible. It is the lowest level of storage and the closest to the hardware.

Datasets : Data sets organized into a table-based, delimited, or record format.

Objects : Data and the associated metadata with it are organized as web-based resources.

Each of the above data storage levels is associated with a certain type of technical interface. This interface corresponds to a particular type of cloud storage device and the cloud storage service used to expose its API.