I cross-posted this in one other popular forum on another site, and hopefully that is not too much. I'm preparing to implement a FQDN change. We're going from short_name.example.com to short_name.xyz.example.com. DNS is already taken care of. I'm not concerned with that part. I'm concerned with local changes. The boxes are running RHEL ES 4 and RHEL ES 3. Here is my plan so far. Files Files I need to modify or at least check that they will still make sense. /etc/hosts (We have lots of friendly names that are only avail in the hosts file). /etc/sysconfig/network /etc/resolv.conf /etc/nsswitch.conf Actions Actions I take after all the files are in place. Run *hostname* to change name. SIGHUP sendmail. On Apache httpd, see if ServerName is inherited from hostname somehow and its effects. Anything on Apache Tomcat to do? Reboot, maybe or definitely? Checks Post-implementation checks. hostname output hostname -s output. domainname output. Oddness in /var/log files. Check user mail for reported problems. Any other way to detect cron job failure? No Nagios alerts. Ensure Nagios alerts can still be sent! Test user functionality of site. Apache httpd log complaining? Tomcat log complaining? How to check db connectivity? Thoughts? What am I forgetting? Where will I get bit in the ass? Thanks, All, and cheers!