[CentOS] sendmail not sending after reboot UPDATE

[Stephen Harris]

On Mon, Jun 09, 2008 at 04:46:47PM -0400, Ray Leventhal wrote:
> >DNS.  It's always DNS :-)

> While I agree, I'm still a bit stumped.  Nothing changed other than a 
> reboot on Sunday afternoon.  I do have Friday's rsync snapshot and running
> diff against the sendmail files (cf/mc) as well as hosts, resolv.conf, 
> etc...all showed no differences.

Ah, there's where the reboot magic comes in.  When you start sendmail it
picks up the resolving configuration when you started.  If nsswitch.conf
or resolv.conf changed _afterwards_ then sendmail may not have noticed....
until you reboot!

Many core configuration files (eg tzdata) has this issue; the relevant
libraries load the configuration at start time.

Now I say "may" in the above because if you have nscd then it's very possible
to change configurations without restarting daemons if you nudge nscd.

But, for safety, changing name resolving configurations is better followed
by daemon restarts or rebooting... just for safety.

-- 

rgds
Stephen