Azure DNS name (servername.location.cloudapp.azure.com) VS internal FQDN (hostname.domain name eg servername.acad.ac.uk) - are they both FQDN?

Tom 21

Hi all,

a somewhat petty question that is bugging me.
When I created a VM in our azure subscription, it has the DNS name in the format of
servername.location.cloudapp.azure.com

Which apparently is a FQDN
(where servername is the hostname and location could be northeurope etc)

However when I log onto the server and check its name via ping -a IP or full computer name it comes out as as:
servername.acad.ac.uk
(where acad is generic UK institution)

Apparently that is a FQDN as well.
Is there concept of internal and external (Azure) FQDN - or what I am misunderstanding?

many thanks

Rajesh Swarnkar 886 Reputation points

2025-01-02T11:42:16.07+00:00
Both are DNS Names of the IP associated with NIC of the VM sourced from different DNS Zones.

servername.location.cloudapp.azure.com : this is the DNS label of the Public IP associated with the VM. Check docs: https://learn.microsoft.com/en-us/azure/virtual-network/ip-services/public-ip-addresses#domain-name-label

servername.acad.ac.uk : This seems that your VM is domain Joined, hence getting its name from Domain controller managed DNS service. https://learn.microsoft.com/en-us/entra/identity/domain-services/join-windows-vm

Accepted answer

SaiKishor-MSFT 17,326 Reputation points

2022-02-23T21:30:13.72+00:00

@Tom I understand that you have questions regarding the Azure FQDN i.e., when you create the VM and add a DNS name in the Portal as shown below:

However, you do not see the same name once you login to the Server/VM in Azure. Is this what you are concerned about? Please correct me otherwise.

The FQDN that is provided here is for the Public IP of the VM. Once you login to the server/VM and do a nslookup for the hostname, you will see the hostname of the private IP of the VM.

In this case, what you are seeing(servername.acad.ac.uk) seems like a private DNS name. Can you confirm what DNS server you are using for this VM/Vnet? Usually it shows up in the NSLOOKUP output.

Thank you!
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2 people found this answer helpful.
Tom 21 Reputation points

2022-03-02T12:31:30.973+00:00

Hi SaiKishor,
thank you for this.

That is really helpful. It makes a bit more sense now.

That is correct - seeing the different FQDN name.

The DNS server appears to be:
Default Server: mw-lu2s0llnn-1f.internal.cloudapp.net

which also comes out at below in response to cloud shell query:

az network nic show -g MyResourceGroup -n MyNic --query "dnsSettings.internalDomainNameSuffix" "z2l1m4dhpn5ejmpzusnkyamond.fx.internal.cloudapp.net"

Does that make sense?
I looked at this - is this related?
https://learn.microsoft.com/en-us/azure/virtual-network/virtual-networks-name-resolution-for-vms-and-role-instances

Your help is much appreciated.

SaiKishor-MSFT 17,326 Reputation points

2022-03-02T19:24:41.437+00:00

@Tom Glad that you have better understanding of the concept now. Yes, the article you shared refers to the three ways to resolve domain names to IPs within Virtual Networks.
Which of the 3 methods are you using for your Virtual Network?

Please note that: If the virtual network is linked to an Azure DNS private zones as a registration virtual network, the reverse DNS queries will return two records. One record will be of the form [vmname].[privatednszonename] and the other will be of the form [vmname].internal.cloudapp.net

Please let us know if you have any further questions and we will be glad to assist you further. Thank you!

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Md Alamgir Hossain 0 Reputation points

2024-02-03T20:35:00.57+00:00

Hello Brother...
I cannot properly add my domain in virtual machine. Please help me to add Cname record.
Thanks.
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KATTUPALLI SUDHAKAR 1 Reputation point

2022-01-25T10:01:23.427+00:00

Please go through it.

https://learn.microsoft.com/en-us/azure/virtual-machines/create-fqdn

Also Check

https://stackoverflow.com/questions/15289835/fqdn-on-azure-virtual-machine
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Tom 21 Reputation points

2022-01-27T16:00:06.03+00:00

Lost my reply so here it is again:

Does goes someway to answering however doesn't answer what is happening re:
when using portal and assigning FQDN (as per first article) you get DNS name (FQDN) of

blah.northeurope.cloudapp.azure.com

whereas logging onto the server, running hostname => returns 'blah'
then nslookup 'blah'
returns: blah.emc.someacademicinstitute.ac.uk

Why are they different? Should't the fqdn on nslookup be same as one setup in portal?
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Azure DNS name (servername.location.cloudapp.azure.com) VS internal FQDN (hostname.domain name eg servername.acad.ac.uk) - are they both FQDN?

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