OpenStack Interview Questions and Answers

Prepare your next OpenStack Interview with these Questions and Answers.

What is OpenStack?

OpenStack is a package of software tools for controlling storage, compute, hypervisors and networking resource in a datacenter. Basically its a software tool for managing IAAS (Infrastructure as a Service) cloud. These days more and more datacenter is migrating to manage its resource on OpenStack.

What are the different OpenStack Services or components?

Horizon: 

The GUI component of OpenStack and being used by component administrator.

Keystone: 

Component that provides mechanism for user authentication.

Glance: 

Maintains & manages images in different format.

Cinder: 

Provides Persistent block storage

Neutron:

 Its provides interface to the networks so that you can access network resources (or you can say "Network as a service").

Nova: 

On user demand, provides instances

Swift: 

It is a storage platform which can be united into application

Ceilometer: 

It provides metering of core components which is used for billing purpose. You have datacenter customers and you want to bill them for its usage.

Heat: 

Offer automated infrastructure deployment

Guava: 

UI component for OpenStack for administrators

Name some hypervisors which OpenStack supports?

(a) Vmware
(b) Xen
(c) KVM
(d) HyperV

What are the modular architectural components of OpenStack?

OpenStack Compute: It maintains huge networks of virtual machines and hypervisors
OpenStack Object Storage: Its a storage system which manages and provides support for object and block storage
Image Service:  This components provides provides discovery and registration for virtual disk images

What are the types of storage provided by OpenStack Compute?

(a) Persistent or Volume Storage
(b) Ephemeral Storage

What is the use of user, role and tenant?

User - member of different projects
tenant - group of users
role - specifies authorization level of the user

What is identity service in openstack?

Openstack identity service is managed by Keystone. Its service is primarily responsibile for:
User Management - Its tracks users alongwith its permission
Service Catalog - As name indicates, it provides catalog for the available service with their api

How to pause and unpause/resume an instance?

To pause an instance - nova pause INSTANCE_NAME
To resume/unpause - nova unpause INSTANCE_NAME

What is the command to create a container?

$ swift post CONTAINER_NAME

What is the command to list and check the status of containers?

To list containers - $ swift list
To check status - $ swift stat CONTAINER_NAME

What are the networking options used in OpenStack?

Flat Network Manager - It doesnt configure ip of the instance and left to system administrator to assign an ip.
Flat DHCP Network Manager -  Its ip is fetched from the subnet.
VLAN Network Manager - Creates a Vlan interface and on each vlan, DHCP server is started to fetch ip for the instances.

What is cells in OpenStack?

Cells functionality enables you to scale up an OpenStack Compute cloud. It supports very large deployment. Here is how its works - the hosts in an OpenStack Compute cloud are partitioned multiple cells/groups, which is configured as a tree.

Cloud Computing Interview Questions

Cloud is an emerging trend these days and that is why these days interviewer is asking more questions on cloud computing. Cloud especially IAAS cloud and virtualization are very close terms and you should also know virtualization interview questions for IAAS. 

Here are some basic questions on cloud computing:

What is cloud computing and why should we go for using cloud computing(advantages)?

Cloud Computing is a model in which configurable and scalable computing resources (storage, network, application etc) are provided as a service to end user over internet with minimal effort.

Basically cloud computing has the following features: 
(a) Utility computing
(b) Programmatic
(c) Grid
(d) On-demand
(e) Scalable
(f) Usage based billing
(g) Virtualization

The advantages / benefits of cloud computing is as under:
(a) Cost effective
(b) Highly scalable
(c) Pay as per use
(d) Only operational expenditure (No setup expenditure)
(e) Data backup 
(f) Quick restore in case of disaster
(g) Software as a service
(h) Minimal management effort
(i) Time Saving

What are different types of cloud?

According to deployment -

• Public cloud
• Private cloud
• Hybrid cloud
• Community cloud

According to service -

• IAAS - Infrastructure as a service
• PAAS - Platform as a service
• SAAS - Software as a service

What is Public cloud?

A non-proprietory model where computing resources such as storage, network, applications etc are available to general public for use. It generally works on pay per use model. It is self managed solution with shared resources (with other public) with very less control over performance factor.

What is Private cloud?

Private cloud is a model where a set of non-shared computing resource is dedicated to a single organization and is secured enough so that no other client from the same datacenter can access it. Alternatively, it can also be deployed in-house by the organisation. Also, it has more control over the performance of computing resource.

What is Community cloud?

A community cloud is a multiple user cloud where infrastructure is shared amongst multiple participating organisations from a specific community with common concerns (for eg. regulatory compliance etc) . With added layer of privacy, security and policy compliance, Community Cloud has the properties of both Public cloud (Pay as per use) as well as that of Private cloud.

What is Hybrid cloud?

Hybrid cloud is the combination of both Public and Private cloud. Suppose an organisation wants to achieve cost-effectiveness with security then hybrid cloud is the best solution. It can setup private cloud for secured sites and public cloud for sites where security is really not a concern. Since public cloud is relatively cost-effective and is highly scalable as compared to private cloud which is more secure, such a setup achieves both security and cost-effective.

That's all for interview questions on cloud computing.