:::. Sendmail & WorkAroundBrokenAAAA.

[David Robillard]

> Thanks for looking into this. I just realised that the domain in
> question got fixed overnight after notifying the sysadmin. I guess this
> is a good thing, yet I'm left puzzled with the difference between
> confBIND_OPTS option and compiled INET6 support.

Hello Mikhail,

The difference is rather simple. The sendmail program will look up
AAAA records only if it is built with the NETINET6 compile-time macro
defined. If so, it looks up AAAA records first, then A records.

Thus, if sendmail is not compiled for IPv6, then the resolver will
never query AAAA records. Hence there will never have a problem
related to the WorkAroundBrokenAAAA.

See 24.9.91 as "ResolverOptions" and 9.2.7 as "Broken IPv6 Name
Servers" in the sendmail book by O'Reilly (the so called Bat Book
ISBN: 1-56592-839-3)

The book recommends the following if you find a broken Name Server:

a) Notifiy the hostmaster running the broken name server. The sooner
the broken name servers are fixed, the cleaner the internet will run.

b) Add the define(`confBIND_OPTS', `+WorkAroundBrokenAAAA')dnl into
your sendmail.mc file.

Regards,

David

-- 
David Robillard
UNIX systems administrator & Oracle DBA
CISSP, RHCE, Sun Certified Security Administrator