This morning we had an DNS outage on one of our servers. Local cron jobs that were trying to connect to local domains were failing with:
Looking up www.example.com
Unable to locate remote host www.example.com.
Alert!: Unable to connect to remote host.
lynx: Can't access startfile http://www.example.com/process.php
After restarting a few services and even restarting the server, nothing worked. After some additional reseach, and a bit of head scratching, I decided to flush the DNS cache to see it that would clear up the problem.
The following command will flush the cache on a Centos server:
service nscd restart
After that, everything was once again running smoothly.