How to create a sub-domain pointing to a name server

domain-name-systemnameserversubdomain

I am trying to set up a sub-domain that points to Azure name servers for App Services so we do not have to add records in the main domain.

For example:

  • Main domain: example.com > DNS provider's name servers
  • Sub-domain: sub.example.com > Azure name servers.

I tested the theory in two public DNS providers and the process was easy and straight forward. I went to the name server records for the prescribed domain and added: 

sub | ns1-02.azure.com
sub | ns2-02.azure-dns.net
etc...

Therefore, any requests pointing to *.example.com would be dealt with by the public DNS's name servers and anything pointing to *.sub.example.com would be dealt with by Azure name servers.

However, we now need to use the customer's actual domain, hosted by Network Solutions and they have a different setup. I can add name servers, however there is no place to add sub, only the name server's FQDN, therefore it looks like entries here would replace their name server with Azures for everything, which is not what we want to do.

Reading their documentation, on adding a sub-domain, it appears they want me to add what I would refer to as an A-record. http://www.networksolutions.com/support/how-to-create-sub-domains/, however, what would that A record look like. @ > ns1-02.azure.com I fear that would break things.

How could I achieve this. I am I forgetting something in DNS 101. Is there a work around / trickery anyone can think of that would allow us to achieve the same goal without having to suggest the customer moves away from Network Solutions or buying another domain?

Best Answer

You have a domain name example.com and a subdomain sub.example.com. You want a different set of nameservers for each so you do a delegation: in the authoritative nameservers for example.com you will need to provide NS records for the sub label pointing to the second set of namerservers.

Of course this second set of nameservers must be configured to be authoritative on sub.example.com otherwise the recursive nameservers chasing the name will come to them and receive an error, hence called a lame delegation.

I have no idea what Network Solutions allows you to do or not. If they do not allow you to change the content of the zone they server for you, you will need to change your DNS provider (it is not necessarily your domain name registrar, it can be but it can be another structure too).

You need to add in your zone something like:

sub NS ns1-02.azure.com.
sub NS ns2-02.azure-dns.net.

using the example you gave. But again, as written above before doing that make sure that ns1-02.azure.com and ns2-02.azure-dns.net are configured to be authoritative on your subdomain sub.example.com.

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