Am I wrong?

[Barry Margolin]

In article <9j1i3n$jkv at pub3.rc.vix.com>,
Nick <nick.cobra at blueyonder.co.uk> wrote:
> This was cut from a post to my ISP's support news group have I got this
>approximately right?
>
>
>"To Tellewest support"
>Why cant your DNS servers see my name server <ns1.cobranetworks.net> I have
>to use BT's DNS to know if I exist
> "I do by the way"
> Has been like this for over a week! any ideas?

Higher-level servers are only queried if you don't have the NS records for
a domain cached.  It's possible for a server to have the following records
in its cache:

cobranetworks.net.     1D  IN NS  ns1.cobranetworks.net.
cobranetworks.net.     1D  IN NS  ns1.granitecanyon.com.
ns1.cobranetworks.net. 1H  IN A   195.82.104.220
ns1.granitecanyon.com. 1D  IN A   205.166.226.38

An hour later, the ns1.cobranetworks.net A record will be removed from the
cache, but the remaining records will still be there.  If someone then
tries to look up ns1.cobranetworks.net, a recursive query will be sent to
ns1.granitecanyon.com.  It's not necessary to consult a .net or root
server, because we still have a usable NS record for cobranetworks.net.

This is why you need to duplicate glue records in the domain itself.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Burlington, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.