If you are looking for OpenStack Interview Questions And Answers for Experienced 2020, you are at the right place. Here Mindmajix sharing a list of 45 interview question on OpenStack. According to the sources, OpenStack has a global share of about 1% and it's growing rapidly. So, You still have the opportunity to move ahead in your career by choosing OpenStack. Mindmajix offers OpenStack Interview Questions that help you in cracking your interview & acquire dream career as OpenStack Engineer.

OpenStack Interview Questions And Answers

Q1. Differentiate between AWS and OpenStack. 

Ans. The main criteria of differences between AWS and OpenStack are as follows –

Points of difference AWS OpenStack
License The license of AWS is Amazon proprietary. Open Source is the license of OpenStack.
Operating medium The medium through which operations are performed repeatedly is by using templates. OpenStack uses text files to perform operations repeatedly.
System of operation       Operates using the system provided by the cloud administrator. Operates by AMIs which are put forward by AWS.

Q2. What is OpenStack?

Ans. OpenStack is a cloud computing system that manages a large volume of storage, compute and networking resources in a data centre with the help of APIs having common authentication methods. It is an open-source software freely available for both public and private clouds where networking resources and virtual servers are made available to users

Q3. Mention the three main components of OpenStack.  

Ans. The architecture of the OpenStack developmental software program is made of three main components -  

1. The image service - The virtual disk images are registered and also discovered by this service provided by OpenStack.  
2. Computing - The management of a large network over the Internet is also done in a good way by OpenStack.  
3. Storing Object - Two types of storage, block and object are both supported by the system of OpenStack. 

Q4. What benefits do you get by using the OpenStack? 

Ans. For the development of any software or for the improvements of any solution, OpenStack can be of great help. It can also develop a SAAS application. These are the following benefits of using OpenStack

  • IT users can be provided with some service storage with the help of OpenStack which acts as a very powerful foundation.  
  • The storage, both block, and objective are provided by OpenStack. These storage provided by OpenStack can be handled easily.  
  • The fees for licensing of running a software program on OpenStack is also less than running on any other platform like VMware.  

Q5. How many types of block storage ads provided by OpenStack?  

Ans. Mainly two types of block storage are provided by OpenStack - 

  • Volume Storage - This type of storage refers to the independent ones. These are persistent in nature.  
  • Ephemeral Storage - This type of storage is an example of a single storage instance. After the termination of a virtual machine, or generally disappears.  

Q6. Where are the VM images stored in OpenStack?  

Ans. The list of locations of VM images are as follows - 

  • File system
  • HTTP  
  • Object storage by OpenStack
  • GridFS
  • Rados Block Device  
  • S3 

Q7. What is the meaning of Cell?  

Ans. For scaling the compute cloud of OpenStack, Cell is used. It functions in a very simple way. Basically, the host gets divided into various groups and these are called cells.  

Q8. List the most important components of identity user management.

Ans. These are the most important components of identity user management -  

  • User - A person, a system or even a service of the OpenStack is often digitally represented.  
  • Tenants - The objects get grouped according to their specific identity. Tenants are the ones who map this grouping to a particular organization, user or even a project.  
  • Roles - It consists of various privileges and rights of users getting to operate a particular function. 

Q9. What is the meaning of the word Token in OpenStack?  

Ans. The token is referred to as the validation required for any kind of authentication. The generation of Token mainly occurs after the insertion of the various credentials which are done by the users. Any type of services provided by OpenStack can be accessed by Token. However, the token can be used for a specified time period and after that, it has to be renewed. The credentials of the users must be authentic in order to create a token. 

Q10. What is the meaning of the term 'Flavor' in OpenStack?  

Ans. OpenStack provides various hardware templates which are found virtually and they are known as Flavor. Generally, the size of the memory of any hard disk and RAM is defined by it. In fact, various components like Name, ID, Disk, Memory are all illustrated by it. The flavor can be modified in the OpenStack.  

Q11.  What are the vital components of OpenStack?

Ans. 

  • Horizon: OpenStack has only 1 GUI and that is the horizon. The component administrators take ideas of the current operations in the cloud after seeing the horizon.
  • Nova: It is the major computing engine that handles various virtual machines (VMs) and computing tasks
  • Swift: It is a robust and reliable storage space for files so that it becomes easy for developers to locate files using a unique identifier.
  • Cinder: It is a block storage system for files just like traditional systems so that files can be accessed speedily.
  • Neutron: It ensures proper connectivity of components while deploying the applications.
  • Keystone: It is a central list to identify all cloud users. It provides mapping techniques to access methods against Keystone.
  • Glance: It is a service provider for images that offers virtual copies of hard disks as images. Images can be used as templates while deploying new applications.
  • Ceilometer: This component is used to provide billing and telemetry services to cloud users. It also maintains a record of component usage by each cloud user.
  • Heat (Orchestration Engine): It is one of the essential components that is used to maintain the cloud infrastructure. Developers can store and orchestrate/illustrate the requirements and resources needed in a cloud application.

Q12. How are the services provided by OpenStack being managed? 

Ans. The services provided by OpenStack are managed with the help of a dashboard named Horizon and is web-based.  

Q13. How do Account Reaper works?  

Ans. Data in the deleted accounts which are not used by the users are removed with the help of Account Reaper.  

Q14. Volume often gets transferred from a user of OpenStack to another. How? 

Ans. Cinder transfer which is considered to be a special kind of command is mainly used to transfer volume between owners.  

Q15. Define bare-metal node. What are its components?  

Ans. The hardware resources can be controlled by users with the help of bare metal nodes which gives the users the right to control the bare metal driver. Its components are -  

  • Bare metal node operating system - The is considered to be the software base for various nodes present in the cluster.  
  • Bare metal node orchestrator - All the nodes when dispatched in the cluster is managed by this software.

Q16. How can the network interface be removed from the bare metal node?  

Ans. By using the command known as the bare metal interface remove, the network interface can be removed from the bare metal node.

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Q17. What do you mean by the term 'Cinder'?  

Ans. The storage in the OpenStack is mainly handled by using Cinder.  

Q18. What types of commands are used for the generation of Key pairs?  

Ans. The following are the different commands which can be used - 

  • cd.ssh
  • ssh-keygen
  • Nova keypair - add - pub_key id_rsa.pub mykey

Q19. How can a user be created in the OpenStack? 

 Ans. The user name is mainly created by the command, sudo nova-manage user.  

Q20. List the functions of Identity Service.  

Ans. There are two main functions. These are as follows - 

  • Service Catalog - The existing services are provided along with the catalog. 
  • User management - Users gets tracked and managed in this way.  

Q21. What is Hypervisor?  

Ans. VMM which is the abbreviation of virtual machine monitor is basically defined by the Hypervisor. It is also used to define various components like firmware, hardware, and software. All these are part of the virtual machine. A hypervisor is mainly consisted or included by the host machine or various other virtually available machines. Multiple Hypervisor is also available in the OpenStack developmental software program and can choose accordingly catering to specific uses.

Q22. What are the different types of Hypervisor available in the OpenStack developmental software program? 

Ans. The following are the lists of Hypervisors available in the OpenStack developmental software program are -  

  • KVM - Kernel Virtual Machine  
  • QEMU - Quick EMUlator and these are used for the purpose of development  
  • LXC - Linux VMs are present in this Linux Containers
  • UML - For the development of the system, User Mode Linux can be used  
  • Hyper-V - Virtualization of the server  
  • VMware vSphere - Includes VMware Linux  

Q23. What work does the Filter Scheduler do?  

Ans. If there is an instance of creating some new functions, the notification is mainly given by the Filter Scheduler. It also helps in filtering these notifications according to their importance. Compute Nodes are the ones with whom it works. The hosts which are unfiltered gets created at first and by the help of their specific properties, it gets filtered. Such filtered hosts are needed according to the total number of instances.  

Q24. What are the different networking options that are available in OpenStack?  

Ans. The following are the different types of networking options -  

  • Capacity Filter - This type of filtering is mainly based on the capacity consumption of the volume host.  
  • Availability Zone Filter - Filter did according to the zones available.  
  • Different Backend Filter - Done by the volume scheduled to the various back end.  
  • Retry Filter - Filtering existing hosts.  
  • JSON Filter  

Some other types of networking options available are - 

  • Flat network manager 
  • VLAN network manager  
  • Flat DHCP network manager  

Hence, OpenStack allows various kinds of networking options to choose from.  

Q25. What is the meaning of OpenStack Python SDK?  

Ans. SDK is the abbreviation form of the Software Development Kit and these are used for writing various python scripts and also managing them. These scripts are well connected with the OpenStack API with the help of SDK. Tasks in Python are also obtained with the help of this by calling on the Python Objects.   

Q26. How can an instance be paused and also unpaused?  

Ans. Two types of command like $ nova pause INSTANCE_NAME and $ nova unpause INSTANCE_NAME are used to pause and unpause instances.  

Q27. What are the various functions of the command 'nova'? 

 Ans. The functions of nova are as follows -  

  • Compute resources are well managed  
  • Authorization and networking  
  • API based on the REST  
  • Communication which is asynchronous  
  • Supports Xen several and is hence considered to be Hypervisor agnostic 
  • Helps in the management of instances  

Q28. How do Swift functions?  

Ans. Swift helps in string various objects. It helps in storing objects which are bigger in size and is also numerous in numbers. It helps in reducing data by storing such objects. Its works are often associated with large number of sets of data. It contains data which are needed for virtual machines and other apps. Swift also has the capability of media streaming and can also secure a large number of objects stored by it. It has extreme scalability skills and can also help in backing up files and data.  

Q29. Define Sanitization Process.  

Ans. Sanitization process refers to the process of the removal of certain information which is present in the media. This type is information is basically useless as these can't be reconstructed or retrieved. This process mainly includes various techniques like purging, clearing, erasing cryptographically and also destruction. Such process prevents the information to get out to any individuals who are unauthorized during the releases of such information in the media. 

Q30. How can you overcome any type of sudden server failure?  

Ans. During the failure of the server or when the server is not seen to be perfectly functioning then the Object Storage services should not be running. Hence, it is best to close them of this problem arises. This is because to know the solution, troubleshooting must be done.

Closing the object storage service will allow it to work or function while troubleshooting is still going on. However, often such failure just needs rebooting and hence for this work which doesn't require much time, the object storage service doesn't need to be closed.  Update to this service will be added once the machine gets online after rebooting.

Removing the drive from the ring is the best idea when the drive can't be replaced. But if it can be replaced, then it can be added back to the ring.

Q31. List the modular architectural components of OpenStack?

Ans.

  • Dashboard
  • Networking
  • Compute
  • Block Storage
  • Object Storage
  • Identity service
  • Telemetry
  • Image Service
  • Database Service etc.
  • Orchestration

Q32. Name the types of storage supported by OpenStack?

Ans. Persistent Storage / Volume Storage: This storage type is created by users and they are independent and persistent of any specific instance. Persistent storage in OpenStack are:

  • Object storage: binary objects can be accessed in this storage via REST API.
  • Block storage: block storage devices can be accessed with this storage by affixing volume with their contemporary VM instances.
  • Shared File System storage: Multiple files can be managed by using this storage system for exchange and storage of files with multiple users simultaneously.
  • Ephemeral Storage: It is used to specify a single instance. It is temporary storage that gets vanished once the VM is terminated.

Q33. What is an Identity Service in OpenStack?

Ans. Keystone executes the complete API for OpenStack therefore it is the most preferred identity service in OpenStack. The Keystone Identity offers service cataloging and user management.  In service catalog, a list of available services are listed in API while in user management users and their respective access permissions are tracked. They are also responsible for providing authentication credential information of users, tenants and roles. Policy and token services are also carried out by Keystone Identity.

Q34. Explain networking techniques used in OpenStack?

Ans. Flat DHCP Network Manager: In this technique, IP addresses are fetched from the subnet for virtual machine instances but IP addresses to VM are allocated by using DHCP (Dynamic Host Configuration Protocol).

Flat Network Manager: In this technique, IP addresses are fetched from the subnet for VM instances, and then inserted into the image while launching.

VLAN Network Manager: VLAN is better and more preferred than the above two techniques as it offers a separate and secure network to virtual machines. There is a physical switch to provide a separate virtual network and separate IP range and bridge to every tenant.

Q35.  Name the Networking hardware used in OpenStack.

Ans. Networking hardware used in OpenStack are Networks, Subnets, Routers and Ports Vendor Plugins

Q34. Write down the order in which nova services can be restarted on a controller node?

Ans. Nova services can be restarted in the following order

  • service nova-conductor restart
  • service nova-cert restart
  • service nova-scheduler restart
  • service nova-consoleauth restart
  • service nova-api restart

Q35. Write a command to get the list of available Floating IPs from the command line?

Ans. The below command can be used to get the list of available floating IPs

~]# openstack ip floating list | grep None | head -10

Q36. What role does API server play in OpenStack?

Ans. An API server is used to provide an interface to communicate with the cloud infrastructure or the external world.

Q37. How to retrieve the console URL of an OpenStack instance from the command line?

Ans. It can be retrieved by using the below command:

~# openstack console url show {instance-id}

Q38. What are the endpoints of OpenStack services?

Ans. Endpoints of Openstack services are classified as:

  •   Public Endpoint
  •   Internal Endpoint
  •   Admin Endpoint

To view endpoints of each openstack service, below command is used

~# openstack catalog list

To list the endpoints of a specific service, below command is used

~# openstack catalog show keystone

Q40. What is the role of cells in OpenStack?

Ans. The hosts get partitioned into groups of cells when the cell functionality gets enabled. These cells are arranged as trees and they have the ability to scale up the OpenStack cloud in a simpler way.

Q41. Name the services that run on a controller node?

Ans. The services that run on a controller node are:

  •   Identity Service ( KeyStone)
  •   Nova Services like Nova API, Nova Scheduler & Nova DB
  •   Image Service ( Glance)
  •   Block & Object Service
  •   MariaDB / MySQL and RabbitMQ Service Ceilometer Service
  •   Orchestration Service (Heat)
  •   Management services of Networking (Neutron) and Networking agents

Q42. Where VMs are located on the Compute Nodes by default?

Ans. VMs, by default are stored in “/var/lib/nova/instances”

Q43. Write down the command to spin a VM from Command Line?

Ans. The command to spin a virtual machine from command line interface is

#openstack server create --flavor {flavor-name} --image {Image-Name-Or-Image-ID}  --nic net-id={Network-ID} --security-group {Security_Group_ID} –key-name {Keypair-Name} <VM_Name>

Q44. Can we see the list of roles and associated IDs in the OpenStack environment?

Ans. Yes, we can see the list of roles and associated IDs by using keystone role-list

Q45. How to assign a project/tenant to a user?

Ans. Project/tenant can be assigned to a user by writing the command sudo nova-manage user create user-name

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