Glue record
A glue record is an A or AAAA record a parent zone publishes alongside an NS delegation, giving the IP address of a nameserver directly instead of making a resolver look it up separately. It's needed specifically when a domain's nameserver is itself a subdomain of the domain it serves (for example, `ns1.example.com` acting as a nameserver for `example.com`), since otherwise resolving that nameserver's address would require already knowing it -- a circular dependency. Without the correct glue record at the registrar, a domain using in-domain nameservers can become unresolvable even though its own DNS zone is configured correctly, because resolvers never get far enough to ask it anything. Glue records live at the registrar/parent-zone level, not inside the domain's own zone file, which is why confirming them means checking what the registrar actually publishes, not just the domain's own DNS records.
By AdminKit team, Netbase JSC · Updated