Resources
What are glue records?
Glue records break the circular lookup that appears when a nameserver lives inside the domain it serves.
If example.com is served by ns1.example.com, a resolver has to know the address of ns1 before it can ask anything about example.com. The registry supplies that address as glue.
Glue is created at the registrar, not in your zone. Changing the address in your zone alone leaves the old glue in place.
Nameservers outside the domain need no glue, which is why using nameserver names from a separate domain is simpler.
If you want to answer under your own nameserver names on our machines, we set the glue with you when the delegation is prepared.