Question : New Sub-Domain DNS Setup

I created a new sub domain 123.xyz.com (We already have another sub-domain 789.xyz.com).  When the domain was created the new Domain Controller serv1.123.xyz.com hosts the AD integrated DNS zone 123.xyz.com.  The servers in both the parent domain xyz.com and the other sub domain 789.xyz.com cannot resolve the the server in the new domain.  They can ping the domain name OK, 123.xyz.com, but not the server serv1.123.xyz.com.  (network connectivity is ok, just not DNS resolution.) I want to change the AD integrated zone replication from domain to forest.  However it's failing because of DNS resolution.

The parent domain and other sub domain do not have a DNS zone for 123.xyz.com, how can I let the parent domain do lookups to the new sub-domain so I can update the DNS replication?

Answer : New Sub-Domain DNS Setup

If the zone exists on the DCs for the new child domain then a Delegation in the parent zone (xyz.com) would be more appropriate.

The delegation is the sign-post, telling the DNS system where to find names for 123.xyz.com.

I'd say this is the most appropriate for your situation.

Chris