[dns-operations] dns loop

[Paul Vixie]

> Now, when writing my own resolver how fast should I timeout if
> it appears to be a loop and should I just detect and not try in
> the first place if I'm directed to server that already answered
> the query (or should I try another server in the same NS list)?

if while iterating you get a referral that doesn't get you closer
to your goal you should ignore it and try other servers for the
same delegation point.  if they all answer nonimprovingly, you
should signal SERVFAIL to your own original requestor.

but this is a protocol/implementation topic not an ops topic?