Cloud Computing Interview Questions


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Cloud is a term used to describe a global network of servers with each having a unique function. It is a vast network of remote servers arranged all around the globe and are hooked together and work in a single ecosystem. These servers store and manage data, run various applications, or deliver content such as streaming videos, web mail etc. Cloud allows you to access file and data from any internet-capable device instead of accessing them from a local or personal computer. Also, no matter where you go or anytime you need, you have access to your data.

Cloud Computing is basically the delivery of computing services which include storage, databases, servers, networking, software, analytics and intelligence. Cloud Computing is implemented over the internet and offers pay-as-you-go services which helps you to reduce your operating costs and run your infrastructure efficiently.

For businesses who consider IT resources to be a major part, Cloud Computing is a big shift from the traditional On-premise Computing. Let us go through some of the reasons for organizations to switch to Cloud Computing.

  • Cost

Cloud computing eliminates the cost of buying hardware, software, racks of servers, and setting up data centers. It saves consumption of electricity for power and cooling and does not require an IT team to manage the infrastructure. It requires OPEX as most of the cloud service providers charge on a subscription basis.

  • Speed

Most of the cloud computing services offer on-demand and self-service. Businesses get a lot of flexibility as a large amount of computing can be achieved in minutes helping them to increase productivity.

  • Global scale

Cloud computing services are highly scalable. It has the capability to deliver the right amount of IT resources such as computing power, storage, bandwidth and so on from an appropriate geographic location.

  • Productivity

On-Premise computing requires regular diagnosis of the system by the IT team and needs to be updated as per business requirements which needs a lot of time. Also, after an upgrade, all the previously configured settings are lost and requires reconfiguration. In the case of cloud computing, it is different. Automatic updates are provided by service providers and does not affect the previous configuration. This allows the IT team to achieve more important goals in a business and increase productivity.

  • Performance

Performance of any computing systems depends on the hardware, software, and servers. It is expensive to install such requirements for an on-premise computing system. However, in cloud computing, you can upgrade your system at any moment at an operating expense. You can use GPU whenever required and pay for the time of use. This allows businesses to run with high performance and without any interruption.

Cloud computing and mobile computing, both use wireless systems to transmit data. Apart from that, both the terms are quite different.

Cloud computing is a specific design of new technologies and services which uses distributed networks to send data through wireless communication. Cloud service providers serve multiple clients and arrange access between closed networks and the client’s local networks. Data across these networks can be accessed by the vendor and can store it securely while they deliver services back to the client.

On the other hand, mobile computing is a function that includes smartphones and tablets performing a lot of operations that traditional desktops or laptop are capable of. It includes accessing internet through browsers, sending and receiving various forms of data, supporting software applications with a core operating system and so on. As an interface, mobile operating system is capable of supporting users by proving familiar search technologies, easy touch-screen commands, and interactive icons.

Some of the essential characteristics of cloud computing include:

  1. On-demand self-service: A user can independently provision computing capabilities such as network storage, server time etc. as per requirement. All of these can be done without any human interaction with each service provider.
  2. Broad network access: Client platforms such as laptops, mobile phones, tablets, and workstations are used to access and promote capabilities that are available over the network through standard mechanisms.
  3. Resource pooling: According to consumer demand, the service provider’s computing resources are pooled to cater to multiple consumers using a multi-tenant model. Resources, both physical and virtual, are dynamically assigned and reassigned as per requirement and demand.
  4. Rapid elasticity: It is a term used for scalable provisioning. It is the ability to provide scalable services rapidly for inward and outward in proportion to the consumer’s demand.
  5. Measured service: This is a service where cloud service providers monitor or measure the provision of services for various reasons which include billing, proper use of resources, or entire predictive planning.

Software as a Service is a software distribution model which provides cloud application platform on which a third-party party provider can host applications and make them available to customers over the internet.

There are three main categories of cloud computing, Saas, IaaS and PaaS. SaaS, among the three, is closely related to on-demand computing software delivery models and application service provider (ASP), where the customer’s software is hosted and delivered by the provider. SaaS applications for business technologies include email, sales management, financial management, customer relationship management (CRM), human resource management (HRM), billing and collaboration.

The different modes of SaaS are:

  1. Simple multi-tenancy: In simple multi-tenancy, each user has their own resources which are not different from other users’ and are not shared with the other users. It is considered as an inefficient mode because the user has to invest more time and money to ass better infrastructure if there is a rise in demand in less time to deliver.
  1. Fine grain multi-tenancy: The functionality is similar to that of simple multi-tenancy where the resources can be shared with many but the efficiency here is higher as the

data and permission within an application are not shared.

Platform as a Service (PaaS) is one of the categories of cloud computing services which provides customers with a platform that allows to develop, run, and manage applications with no complexity of building or maintaining the infrastructure which are typically related to developing or launching an application.

PaaS is an important layer in the cloud architecture. It is completely built on the infrastructure model and provides resources such as network and storage. This layer organizes and operates the resources provided by the immediate layer. It also provides virtualization of the infrastructure layer and makes it look like a single server.

Communications as a Service (CaaS) is one of the categories of cloud computing services is a solution available on lease from a single vendor for enterprise communication. It includes communication services such as VOIP (voice-over internet protocol), instant messaging services, video-conferencing applications etc.

IaaS or Infrastructure as a Service is one of the three main categories of cloud computing services. It provides virtual computing resources over the internet.

The resources provided by Infrastructure as a service (IaaS) are both physical and virtual which are used to build a cloud. Infrastructure such as storage, servers and other hardware systems, deals with the difficulties faced while maintaining and deploying the services provided by this layer.

Web Application
Cloud Application
It is exclusively designed to be used from a web browser
It is not always dependent on web browsers to work
Located elsewhere and are accessible from almost anywhere
Majority of the compute cycles happen in a data center somewhere else
Limited scalability
Inherently scalable
Limited availability
Very high up-time
User data & business processes stored in a single data center
User data & business processes stored in multiple replicated data centers
Only runs on provider’s web servers
Can run on the users computing systems or the provider’s web servers
Each customer uses their own instance of the application
The provided application is standardized for all customers
Isolated-tenancy solution
Multi-tenancy solution

There are many providers for cloud computing services. Some of the large cloud providers along with their databases are mentioned below:

  • Google Bigtable - Bigtable by Google is a hybrid cloud which contains a big table split into further tables and rows. Bigtable is a high performance, compressed, proprietary data storage system built using Google File System, SSTable, Chubby Lock Service and other technologies developed by Google.
  • Amazon SimpleDB - SimpleDB by Amazon is a distributed database used for indexing and querying data. It is a web service used with Amazon S3 and Amazon Elastic Compute Cloud, a part of AWS, and allows creating, storing, and processing query on the data set within the cloud platform. It has the capability to index the data automatically.
  • Cloud-based SQL - It was introduced by Microsoft and is based on SQL databases. Cloud-based SQL provides data storage by using relational model in the cloud. The data is accessible from the cloud by using client application.

There are a lot of advantages of cloud computing. Some of them are mentioned below:

  • Cost is low: Cloud computing services are free from capital expenditure. There are pay-as-you-go subscription basis charges that apply, therefore there is no huge cost of hardware involved in cloud computing.
  • Availability: Most of the cloud providers are available 24X7. They offer services and maintain an uptime of 99.9%. Users can access the applications from anywhere, in fact some of the applications even support off-line.
  • Flexibility in Capacity: Cloud computing services provide facilities which can be used to turn off, up or down as per user’s choice and circumstances. 
  • Automatic Updates of Software: The service providers update the software on a regular basis which also includes updates on security.
  • Security: Cloud computing offers high security of data. Data in an on-premise device may have the risk to be stolen or deleted. In cloud computing, you can remotely wipe data as well as assign access to designated people in your company and also follow their operations performed on a daily basis.
  • Carbon Footprint: Cloud computing is supporting organizations to reduce their carbon footprint. Organizations are utilizing the number of resources required and this helps them to avoid any kind of over-provisioning. This results in no wastage of energy and resources.

The different layers associated with cloud computing architecture are -

  • Cloud controller or CLC: In the hierarchy, it is the topmost layer which is used to manage virtualized resources such as networks, servers, storage with the user APIs.
  • Walrus: It acts as a storage controller and manages the demands raised by users. To maintain the virtual machine images and user data it maintains a proper scalable approach.
  • Cluster Controller or CC: This is basically used in order to control and execute all the virtual machines. It manages the virtual networking between external users and virtual machines.
  • Storage Controller or SC: It is in the block form and provides a storage area which is attached dynamically with the virtual machines.
  • Node Controller or NC: It lies in the lower level in the hierarchy and provides acts as a hypervisor which controls the virtual machine activities. It also includes execution, management and termination of various instances.

On-demand functionality in cloud computing is a delivery model in cloud computing in which resources of computing are made available to the user as per need. The resource can be maintained from the user’s end or by the cloud service provider. It uses a shared pool of networks, servers, storage, applications and provides configurable resources to users.

Hybrid cloud is a cloud computing environment which is basically a composition of two or more clouds. It can be a combination of private and community, or private and public and so on. It is bound together and offers the benefit of multiple deployment models. Hybrid cloud also has the ability to connect collocation, dedicated and/or managed services with cloud resources.

Public Cloud
Private Cloud
Hybrid Cloud
Very high
Very high
Most secure
Very secure
Low to medium
Very good
Medium to high
Pay-as-you-go model
Fair, but needs on-premise hardware
Decent, as it allows some resources to a pay-as you-go model

Cloud computing supports a lot of databases. Some of the open source databases that are developed to support are mentioned below:

  1. MongoDB: It is an open source database system. It is a document-oriented database and free of schema. It has been written in C++ and provides high storage space and tables.
  2. CouchDB: It is also an open source database system which is based on Apache Server and is mostly used to efficiently store data.
  3. LucidDB: It is an exclusive database for data warehousing made in JAVA/C++. It provides various functionalities and features to maintain data warehouse.

Scalability:  It is a term used to define the characteristics of cloud computing through which workload is handled by escalating in proportion amount of resource capacity. It allows the architecture to provide on-demand resources when the traffic raises a requirement.

Elasticity: It is a term used to define the characteristics which provides the concept of commissioning and vice-versa of large amount of resource capacity dynamically. The speed by which the resources are coming on demand and the usage of the resources are used to measure elasticity.

There are many platforms which are used for cloud computing. Some of the platforms used for large scale distributed cloud computing are mentioned below:

  • MapReduce: It is a programming model composed by Google in order to support distributed computing. It is basically a framework which is capable of working on a large data set. It also makes utilization of the cloud resources and then distributes data to clusters. It can deal with both structured and unstructured data.
  • Apache Hadoop: It is a collection of open source distributed computing platforms. It has been written in Java. It basically creates a pool of computers with each computer having a hadoop file system. Later it creates clusters out of data elements and applies similar hash algorithms. It then creates a copy of the existing files.

The different data types used in cloud computing includes emails, contracts, images, blogs, boolean, locale, decimals, number etc. as the amount of the day increases with increase in days, cloud computing will require efficient data types to store them.

Security plays a vital role with any application and service used by the user. All organizations are always concerned about the security provided with the cloud. There are levels of security which are provided along with cloud environment:

  • Identity management: This level authorizes the hardware component or application service to be used by authorized users.
  • Access Control: This level allows permission to users so that organizations have control and access over other users who are a part of the cloud environment.
  • Authorization and Authentication: This gives a provision to allow people who are authorized and authenticated to change and access the application and data.


In cloud computing, system integrators play a very important role by providing strategies for the complicated processes which are used to design a cloud platform. Integrators plan the cloud strategy implementation for the users which include well-designed architecture to find resources and other characteristics required for cloud computing. Integrators are aware of the creation of data centers and also have the ability to create accurate private and hybrid cloud.

Eucalyptus stands for “Elastic Utility Computing Architecture for Linking Your Programs to Useful Systems”. It provides an open source software infrastructure in order to implement clusters in cloud computing platforms.

EUCALYPTUS is used for building public, private and hybrid clouds. It also has the ability to produce your own datacenter into a private cloud and allows you to extend the functionality to other organizations. EUCALYPTUS provides APIs which can be used to along with the web services to cope up with the demand of resources used in the private clouds.

There are certain essential parameters to be followed before a user is going for cloud computing services -

  • Data integrity: User should be aware of the data integrity in cloud computing. It is a measure to that the data is accurate, reasonable and complete.
  • Loss of data: Users should be aware of the provisions available in the case of loss of data in order to get backup and recovery.
  • Compliance: Users should check that proper rules and regulations are maintained during implementation of the structure.
  • Business continuity plans: Users should check for the service provider and be sure that uninterrupted data resources are received.
  • Uptime: User should be aware of the uptime provided by the cloud computing platform and the ways it can be helpful to businesses.
  • Data storage costs: Users should know the price to be paid for cloud computing.

Cloud computing comprises of different data centers for deployment of cloud computing:

  • Containerized data centers - These are the packages which contain a consistent set of servers, network components, and storage which are delivered to large warehouse kind of facilities. Relatively, each deployment is unique.
  • Low-density data centers - If a data center is containerized it may cause heavy density and in turn will cause heat and other engineering problems. Low-density data centers solve this problem.

The major uses of Application Programming Interface in cloud services are:

  • It eliminates the workload efficiently in order to write fully-fledged programs.
  • It provides a very easy solution to create applications and link the cloud services to other systems.

Cloud computing runs on the concept of data center and it is the data center which is based on the traditional one. Let us see the differences.

  • Cost of traditional data center is higher compared to cloud computing infrastructure
  • Maintenance is high in the case of traditional data centers whereas cloud platform requires minimum maintenance and is not very complicated to handle it.

VPN stands for virtual private network. It is a private cloud which is used to manage the security of data while it is transported in the cloud environment. It is VPN which allows organizations to convert a public network into a private network and use it for file transferring and other resources in a network.

The optimizing strategies used are -

  • Cost optimization and resource optimization are achieved by the concept of three-data center which provides backup if there is a requirement for disaster recovery. It also allows to keep all data intact if there is a failure in the system.
  • By carrying out pre-emptive tasks on the services, system management is improved and made efficient.
  • Security is more advanced and allows only limited users to access the services.

VPN mainly consists of two important things:

  1. Firewall - It filters the messages that get exchanged between networks and act as a barrier between a private network and public network.
  2. Encryption - It is mainly used for protection of the sensitive data from hackers and spammers. A key is shared in the form of a message in order to access.

Virtualization is considered as the foundation of cloud computing. It enables creation of an intelligent layer of abstraction in order to hide the hardware or software intricacies which underlying the layer. VMware is one such virtualization platform that provides the provision to create private cloud and act as a bridge to connect private cloud with external cloud.

There are three key features which need to be identified in order to make a private cloud:

  • Cloud operating system
  • Managing the service level policies
  • Virtualization does not allow the user level and backend level concepts to connect and therefore a seamless environment is created between both.

