Azure Virtual Machines – Interview Questions

1. What is a Virtual Machine? When should you use Virtual Machines in Azure?

Virtual machines are part of the Infrastructure as a Service (IaaS) offering.​ IaaS is an instant computing infrastructure, provisioned and managed over the Internet.​ Quickly scale up and down with demand and pay only for what you use.

​Typically, you’ll choose a virtual machine if you need more control over the computing environment than the choices such as App Service (PaaS). ​

Azure Virtual Machines provide you with an operating system, storage, and networking capabilities where we can run almost any type of applications.​

2. Which type of Virtual Machines did you create?

There are many Virtual Machine series available in Azure.

Some examples are

D-Series – General purpose compute
E-Series – Optimised for in-memory hyper-threaded applications
F-Series – Compute optimised virtual machines
G-Series – Memory and storage optimized virtual machines

3. What are the various components of Virtual Machines?

Virtual machines are associated with multiple other components.

  • Virtual Network
  • Subnet
  • IP address
  • Network security Group
  • Network Interface Card
  • Storage account
  • Finally a virtual machine

Virtual machines are directly associated with NIC Card. And NIC card is associated with NSG and IP address. This is the association between various components of Azure virtual machines.


4. What is a Disk.

Disks are like a physical disk in an on-premises server. we can create managed disks by specifying the following.

  • Disk Size
  • Disk Type

5. Is it possible to expand the size of OS Disk?

Yes. It is possible to expand the OS disk. However, the resizing is possible only when the VM is deallocated. A feature called Resize without downtime (Preview) allows us to expand the OS disk without any downtime.

6. What are managed Disk Types?

Below are the 4 different Managed Disk Types

  • Ultra disks
  • Premium SSDs (solid-state drives)
  • Standard SSDs
  • Standard HDDs (hard disk drives)

7. What is the maximum size of OS Disk in a Virtual Machine?

The maximum allowed is 4,095 GB for OS disks.

8. What is the difference between Managed Disks and Unmanaged Disks?

  • Managed Disk: In Managed disk storage accounts creation & management is done automatically by Azure.
  • Unmanaged disks: In Unmanaged disks, we need to create the storage accounts.

9. What is an Availability Set?

An Availability Set is a logical grouping of VMs which provides redundancy and availability. It is recommended that two or more VMs are created within an Availability Set to meet the 99.95% Azure SLA

Each virtual machine in the Availability Set is assigned an Update Domain and a Fault Domain.

An Availability Set contains a maximum of 3 Fault Domains and 20 Update Domains

Fault Domains define the group of virtual machines that share a common power and network switch

Update Domains indicate groups of virtual machines and underlying physical hardware that can be rebooted at the same time

10. Is it possible to add a Virtual Machine to an Availability Set after the Virtual Machine is created?

No. It’s not possible. We need to add the VM to Availability Set while creating the Virtual Machine.


11. What is Network Security Group?

Network Security Group is a set of rules which are used to filter the traffic to and from Azure resources in an Azure virtual network.

There are two types of NSG rules

  • Inbound Rules are used to control the incoming traffic
  • Outbound Rules are used to control the outgoing traffic

12. How do you create Network Security Group rules?

We need to provide the below for creating an NSG rule

  • Name
  • Priority
  • Source
  • Destination
  • Protocol
  • Port Range
  • Action

13. How do you block accessing the Internet from within the Virtual Machine?

With Security Rules (for inbound and/or outbound traffic) it’s possible to block outgoing internet traffic using the service tag Internet in the Security Rule.


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