Cloud Computing Interview Questions and Answers

Cloud computing is an information technology (IT) paradigm that enables ubiquitous access to shared pools of configurable system resources and higher-level services that can be rapidly provisioned with minimal management effort, often over the Internet. Cloud computing relies on sharing of resources to achieve coherence and economies of scale, similar to a public utility.

Third-party clouds enable organizations to focus on their core businesses instead of expending resources on computer infrastructure and maintenance. Advocates note that cloud computing allows companies to avoid or minimize up-front IT infrastructure costs. Proponents also claim that cloud computing allows enterprises to get their applications up and running faster, with improved manageability and less maintenance, and that it enables IT teams to more rapidly adjust resources to meet fluctuating and unpredictable demand. Cloud providers typically use a “pay-as-you-go” model, which can lead to unexpected operating expenses if administrators are not familiarized with cloud-pricing models.

While the term “cloud computing” was popularized with Amazon.com releasing its Elastic Compute Cloud product in 2006, references to the phrase “cloud computing” appeared as early as 1996, with the first known mention in a Compaq internal document.

What is Cloud Computing?

Cloud computing (also called “the cloud”) describes the act of storing, managing and processing data online as opposed to on your own physical computer or network. Cloud computing is a method of delivering technology to the consumer by using Internet servers for processing and data storage, while the client system uses the data. In general, cloud storage operates through a web-based API that is remotely implemented through its interaction with the client application’s in-house cloud storage infrastructure for input/output (I/O) and read/write (R/W) operations

See More:What is Cloud Computing? And Main service models of cloud computing

What is an open source cloud?

Open-source cloud may also refer to any cloud service that provides open-source software or service to end users or businesses. Open source is a type of program that is available to the general public along with its source code. This means that this program can be altered by programmers to fit the requirements of the company. Below are some examples of open source cloud.

OpenStack is an open source project for creating and managing cloud infrastructure, including storage, compute power, and networking, as well as many related projects to help handle everything from identity management to database deployment.

Linux containers are emerging as a way to develop applications more natively for the cloud, relying upon functionality built in to the Linux kernel as a faster alternative to virtual machines, with projects like Docker helping developers to get started with building containers, and Kubernetes for orchestrating applications made up of many containerized parts.

Big data and the Internet of Things are two users of cloud computing resources where many of the tools powering applications are being developed entirely in the open.

And many more, from the traditional Linux and Apache and MySQL and PHP web server stack to everything from cloud storage applications to collaborative online editors .Open Nebula, Open Stack and Virtual Box are common examples of open-source cloud.

What is a cloud service?

What are the different types of cloud computing services?

The main three types of cloud computing services are:

Software as a Service (SaaS) (End user Customers): Software as a Service (SaaS) is a software distribution model in which applications are hosted by a vendor or service provider and made available to customers over a network, typically the Internet. SaaS has become increasingly prevalent delivery model as underlying technologies that support Web services and service- oriented architecture (SOA) mature and new development approaches, such as Ajax, become popular. SaaS is closely related to the ASP (Application service provider) and on demand computing software delivery models. Using the cloud, software such as an internet browser or application is able to become a usable tool.

SaaS Examples: Google Apps, Salesforce, Workday, Concur, Citrix GoToMeeting, Cisco WebEx

Infrastructure as a Service (IaaS) (Developers): Infrastructure as a Service (IAAS) is a form of cloud computing that provides virtualized computing resources over the internet. In an IAAS model, a third party provider hosts hardware, software, servers, storage and other infrastructure components on the behalf of its users. IAAS providers also host users’ applications and handle tasks including system maintenance backup and resiliency planning.

IaaS Examples: Amazon Web Services (AWS), Cisco Metapod, Microsoft Azure, Google Compute Engine (GCE), Joyent.

Platform as a Service (PaaS) (System Admins): Platform as a Service (PaaS) is a cloud computing model that delivers applications over the internet. In a PaaS model, a cloud provider delivers hardware and software tolls, usually those needed for application development, to its users as a service. A PaaS provider hosts the hardware and software on its own infrastructure. As a result, PaaS frees users from having to install in-house hardware and software to develop or run a new application. The branch of cloud computing that allows users to develop, run, and manage applications, without having to get caught up in code, storage, and infrastructure and so on.

PaaS Examples: Force.com, App Engine, Azure

These longer list will include also cloud computing services.

Backend as a Service (BaaS)
Desktop as a service (DaaS)
Storage as a service (STaaS)
Security as a service (SECaaS)
Data as a service (DaaS)
Workplace as a Service (WaaS)
Hardware as a Service (Haas)
Everything as a Service (EaaS)
Test environment as a service (TEaaS)
API as a service (APIaaS)

What is the use of API’s in cloud services?

What are the different modes of software as a service?

Software as a Service provides cloud application platform on which user can create application with the tools provided. The modes of software as a service are defined as:

Simple multi-tenancy: in this each user has its own resources that are different from other users. It is an inefficient mode where the user has to put more time and money to add more infrastructure if the demand rises in less time to deliver.

Fine grain multi-tenancy: in this the functionality remains the same that the resources can be shared to many. But it is more efficient as the resources are shared not the data and permission within an application

What is CaaS?

What are the benefits of Cloud Computing?

Reduced costs
Better disaster recovery: Cloud-based backup solutions tend to be relatively inexpensive and easy to use. The cloud computing model also means key files aren’t trapped on individual machines, which will inevitably fail at some point.
Capital expenses can be converted into operating expenses.
Cloud customers can focus on rapid innovation without the expense and complexities of hardware procurement and infrastructure management.
End-user productivity is likely enhanced because no software is installed, configured, or upgraded on personal devices, and services can be accessed from anywhere.
Infrastructure functionality, performance, reliability, and security are likely to improve because customers can benefit from “vertically integrated” stacks that are customized at every level — which would be out of reach for on-premises deployments built from off-the-shelf components.

What is the difference between cloud computing and mobile computing?

What are cloud deployment models available in cloud computing?

What is public cloud?

What is private cloud?

A private сlоud infrаѕtruсturе is рrоviѕiоnеd for еxсluѕivе uѕе by a single оrgаnizаtiоn соmрriѕing multiple соnѕumеrѕ (e.g., buѕinеѕѕ units). Private cloud allows organizations to benefit from the some of the advantages of public cloud — but without the concerns about relinquishing control over data and services, because it is tucked away behind the corporate firewall.

What is hybrid cloud?

Hybrid cloud is perhaps where everyone is in reality: a bit of this, a bit of that. Some data in the public cloud, some projects in private cloud, multiple vendors and different levels of cloud usage. Hybrid deployment architectures can be complex and challenging to create and maintain due to the potential disparity in cloud environments and the fact that management responsibilities are typically split between the private cloud provider organization and the public cloud provider.

What is community Cloud?

Community cloud: The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises. Or a community cloud is similar to a public cloud except that its access is limited to a specific community of cloud consumers. The community cloud may be jointly owned by the community members or by a third-party cloud provider that provisions a public cloud with limited access.

What is federated cloud?

A federated cloud (cloud federation) is the deployment and management of multiple external and internal cloud computing services to match business needs. The federation of cloud resources is facilitated through network gateways that connect public or external clouds, private or internal clouds (owned by a single entity) and/or community clouds (owned by several cooperating entities); creating a hybrid cloud computing environment.

What is Multi-clouds and Inter-clouds?

The Intercloud deployment model provides a basis for provisioning heterogeneous multi-provider cloud based project oriented infrastructures on-demand .The first and most powerful idea is for the providers to connect, and provide a seamless integration of their public clouds, just as the internet is. Just as the Internet connects to nearly everything these days, so would the Intercloud. The Intercloud deployment model provides a general framework for multi-provider heterogeneous cloud based services and infrastructures building and operation.

What are the different layers which define cloud architecture?

CLS: Cloud controller or CLC is at the top and is used to manage virtualized resources like servers, network and storage.
Walrus: Walrus is the next layer and used as a storage controller to manage the demands of the users.
CC: Cluster Controller or CC manages the virtual networking between Virtual machines and external users.
SC: Storage Controller or SC is a block-form storage device, dynamically attached by Virtual machines.
NC: NC or Node Controller It acts as a hypervisor and controls the VMs activities such as execution, management and termination of many instances.

What are system integrators in Cloud Computing?

What is Eucalyptus?

What is CLS?

The Cloud Controller (CLC) is the main controller component responsible for managing the entire system. It is the main point of entry into the Eucalyptus cloud for all users and administrators. The Cluster Controller is responsible for maintaining all instances of the virtual network. The Walrus (W) is the controller that sends messages of access to storage devices within Eucalyptus. The Storage Controller (SC) is the storage service within the Eucalyptus that is implemented in cloud interface.

What is the difference between scalability and elasticity?

Scalability is a characteristic of cloud computing which 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 requirement is being raised by the traffic. Whereas, Elasticity is a characteristic which provides the concept of commissioning and decommissioning of large amount of resource capacity dynamically. It is measured by the speed by which the resources are coming on demand and the usage of the resources.

What are the building blocks in cloud architecture?

How can our company benefit from cloud computing?

What are the different datacenters deployed in Cloud computing?

Cloud computing is made up of various datacenters put together in a grid form. It consists of different datacenters like:

Containerized Datacenters: These are the traditional datacenters that allow high level of customization with servers, mainframe and other resources. It requires planning, cooling, networking and power to access and work.

Low-Density Datacenters: These datacenters are optimized to give high performance. In these datacenters the space constraint is being removed and there is an increased density. It has a drawback that with high density the heat issue also creeps in. These datacenters are very much suitable to develop the cloud infrastructure.