Manually creating Glue Records

To create a Glue Record and delegate a subdomain for h.example.com, the following must be added to the example.com zone:

h.example.com.        NS      ns1-h.example.com.
ns1-h.example.com     A       51.215.158.125

It can be tested on the machine running the DNS with:

$ dig +short some-host.h.example.com
some-host.h.example.com.
151.10.158.12

Assuming that some-host.h.example.com is defined in the DNS server running at 51.215.158.125.

It will take time for ns1-h.example.com to propagate, reason why there is a delay until the same test can be done from any machine.