Wietse Venema:
Apparently postfix missed the switching of nameservers and did not learn
of the new DNS until restart. Is this a bug or a feature?
Like most programs, Postfix never reads /etc/resolv.conf.
Yes, I suspected that.
Instead, that file is read by the NSSWITCH system library functions,
and the DNS system library functions.
Postfix does not run on bare metal - instead it runs on an operating
system that provides libraries and other runtime support.
The strange thing is that postfix apparently was the only application on
that box, which was unable to resolve names after the change of DNS.
Following a restart it worked fine.
So it must be something running in the context of postfix, e.g. a
library, which causes the problem. I just try to figure out, what
postfix does differently as compared to roughly a dozen of other
applications, which were subject to the same change of DNS and
eventually use the same system libraries. I'm just the kind of guy, who
likes to know why something is happening.
Since there are a lot of applications inventing wheels (the broken bind9
apparently crashes in its self-made memory manager), knowing that
postfix doesn't is a useful input. Thanks a lot.
Regards,
- lars.
