DNS Delegation

When you create a delegation in NIOS, make sure that the “Name” of the delegated name server is the correct FQDN of the name server(s) you are delegating to (in addition to the IP addresses you set). If NIOS is authoritative for the FQDN's zone, then a “system” record is automatically created for the FQDN that cannot be deleted. If NIOS is recursive, then NIOS will resolve the delegation for recurring queries. For non-recursive queries (+norecurse in DIG) or for recursive queries to NIOS that isn't configured for recursion, NIOS will return FQDN but not IP.

If you change the FQDN of a delegation server, the existing system record will be removed.

If NIOS is not authoritative for the FQDN of the delegation server, it will try and resolve the FQDN to get the IP (even though the delegation config already has the IP) and recurse the answer for the client.

i.e. on a recursive server, a properly configured delegation zone acts like a conditional forwarder.

If the FQDN of the nameserver for a delegation is inside the delegation itself, the NIOS will auto-add glue records when queried for the hosts in the delegation.