[CentOS] Mail has quit working

Sun Aug 26 16:34:34 UTC 2018
Gordon Messmer <gordon.messmer at gmail.com>

On 08/26/2018 06:25 AM, TE Dukes wrote:
> Made the change above in nsswitch, rebooted, ran dig @localhost localhost +short
> Got: dig: couldn't get address for 'localhost': failure

That's a secondary issue.  A properly configured DNS server *should* 
answer correctly for "localhost".  Yours doesn't.  It's broken.  Red Hat 
ships ISC Bind with a working configuration (/etc/named.rfc1912.zones).  
I'm not sure whether you're using something else, or if you've removed 
the RFC1912 zones.  Fix that later.

"host" and "dig" are both DNS tools, and won't tell you if your files 
are being used properly.  While you're troubleshooting the libc name 
resolution system, use "getent".  "getent hosts localhost" and "getent 
hosts" should return something that looks vaguely like the 
data in /etc/hosts.  You can also verify that it works in practice using 
"telnet localhost 25" to verify that you can reach services running on 
the local system.