Alias records

Question

Hello,

I am a beginner. Please explain me 2 things - the word 'instance' - VM instances, container instances etc. - does it mean that original VM or container -created has another virtual replica?

Also, the term 'alias records'

I am looking at this text from the module:

Can this be explained in more simple way? Is Alias record only used when the IP address of the resource changes? So, for example, lets say I made a VM in the Azure portal and then there would be a Alias record for it. Is that right? Now, if I change the resource or let's say move it from Resource Group (RG)- A to some other RG - B, the alias record will point to the VM instance in the new RG?

Does this mean that original VM stays in the RG-A and it has an instance in RG-B?

Also can I say, a VM is an instance of an OS and its applications?

Thank you for your help

Best

Marouf

Answer 1

Hi Marouf Ali,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

the word 'instance' - VM instances, container instances etc. - does it mean that original VM or container -created has another virtual replica?

In the context of virtualization, an instance refers to a single copy of a virtual machine or container that is running on a physical host. When you create a virtual machine or container, you are essentially creating an instance of it. Each instance is a separate copy of the original VM or container, with its own resources and settings. It doesn't mean a virtual replica of an original. Instead, it refers to a single, standalone copy of a virtual machine (VM) or container.

the term 'alias records'

Azure DNS alias records are qualifications on a DNS record set. They can reference other Azure resources from within your DNS zone. For example, you can create an alias record set that references an Azure public IP address instead of an A record. Your alias record set points to an Azure public IP address service instance dynamically. As a result, the alias record set seamlessly updates itself during DNS resolution.

when you create a VM in Azure, you can create an alias record for it that maps a domain name to its DNS name. If you move the VM to a different resource group, the alias record will still point to the VM, as long as the DNS name remains the same. The original VM will still be in the original resource group, and there will not be a separate instance of it in the new resource group.

Refer this link for details about alias record:

Alias records overview - Azure DNS | Microsoft Learn

Does this mean that original VM stays in the RG-A and it has an instance in RG-B?

No, that's not the case. When you move a VM from Resource Group (RG) A to RG B, the original VM itself is moved to RG B. There isn't a replica left behind in RG A.

VM is an instance of an OS and its applications?

Yes

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