The domain rspb.org.uk has the nameservers
ns1.namecity.com. ['62.128.193.35'] (NO GLUE) [TTL=172800]
ns2.namecity.com. ['84.22.161.171'] (NO GLUE) [TTL=172800]
And on the website intoDNS, there is this warning:
The parent nameserver ns1.nic.uk is not sending out GLUE for every nameservers listed, meaning he is sending out your nameservers host names without sending the A records of those nameservers. It's ok but you have to know that this will require an extra A lookup that can delay a little the connections to your site.
In the registrar's settings, I can change these nameservers, but it only allows names, not ip addresses.
My question is, how does the DNS server know the ip address of the nameservers?
I did read somewhere that all nameservers must first be registered in the registry so perhaps an IP address is required during this step. The intoDNS warning mentions "an extra A lookup". Where is the DNS looking?