Glue Records for TLDs

[Stefan Probst]

Dear all,

according to my little understanding, you need "glue records" in the
parent's zone, if you want an authoritative NS having a host name inside
the domain it is serving:

subdomain     IN NS ns.subdomain.domain.com. ; NS inside subdomain
ns.subdomain  IN A  x.x.x.x                  ; that's the glue record (?)

On the other side, the root servers are not authoritative (or something
like that), but are always only referring to another name servers, which
might mean, that they do not have "glue records".
Which would mean again, that an authoritative name server for a TLD
cannnot be in the form of "ns.TLD" (with "TLD" being the domain it is
supposed to be authoritative for).

Is my understanding correct?

Thanks for your help!

Stefan