:::. Sendmail & WorkAroundBrokenAAAA.
david.robillard at gmail.com
Wed Jul 19 14:29:05 UTC 2006
> 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.
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
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.
UNIX systems administrator & Oracle DBA
CISSP, RHCE, Sun Certified Security Administrator
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