Where does the “A” record go for a sub-domain

a-recorddomain-name-systemglue-recordsubdomain

I'd like to create a sub-domain, like sub.example.com.

I have already configured example.com with NS "glue" records to point to the DNS server which will manage the sub-domain. They look like:

sub    IN    NS    other.dns.server.example.com.

Where do I put the A record for sub.example.com?
Do I put it on the DNS server for example.com like:

sub    IN    A    192.168.0.1

Or do I put it in the DNS server for the sub-domain (in my example, other.dns.server.example.com), like:

@      IN    A    192.168.0.1

Or should I put it in both?

I've tried different combinations already, but I want to know what the right way to do it is.

Best Answer

  1. You must put the A record for the subdomain in the domain's records if it does not have any NS records.

  2. You must put the A record for the subdomain in the domain's records if it is a nameserver for itself. (Otherwise, you have a chicken and egg problem.)

  3. You may put the A record for the subdomain in the domain's records even if neither of the first two conditions apply. This has the advantage of saving clients who just need the A record from having to query the subdomain's nameservers, though they may ignore it anyway.

Related Topic