Question

Clearly I don’t know much about DNS, so bear with me on this issue, which has been puzzling me me for a while.

Some WHOIS records show (say) ns1.example.com and ns2.example.com as name servers for example.com. Then how is the actual IP address found? Isn’t this circular?

Answer 1

This question probably belongs on Severfault rather than Stackoverflow, but for the explanation you should read about glue records.

Name servers in delegations are
identified by name, rather than by IP
address. This means that a resolving
name server must issue another DNS
request to find out the IP address of
the server to which it has been
referred. If the name given in the
delegation is a subdomain of the
domain for which the delegation is
being provided, there is a circular
dependency. In this case the
nameserver providing the delegation
must also provide one or more IP
addresses for the authoritative
nameserver mentioned in the
delegation. This information is called
glue. The delegating name server
provides this glue in the form of
records in the additional section of
the DNS response, and provides the
delegation in the answer section of
the response.

There is also a nice explanation in this FAQ.