If these are on VM's the server can become unlicensed when the emulated hardware changes. Can you confirm this is the case?
I was wrong - OS is Centos 5.2 64 bit.
Servers are not on a VM.
I know that Centos isn't technically supported till a later BL Version, but would that be sufficient to cause this issue or do you think I need to look elsewhere for a cause?
I've been using it on Fedora, CentOS, OpenSuSE just fine, no license issues, so I don't think that's the problem (though those OSes are mostly not supported).
Does the box use dhcp? were there changes to the hosts file or 'hostid' somehow?
No dhcp or hostid changes. Engineer says "It's possible hosts file is modified on few servers." but I suspect he means just additions/subtractions, not the server's info itself.
After last night's update server run, and another this morning against 3 remaining, I'm currently at 1 server unlicensed, down from 8. No licensing efforts during that time frame. It's weird, and intermittent and random.
usually the only things that make the host go unlicensed (linux) are if it's a vm and you've got some dynamic cpu going on, or dhcp (host file changes for the host itself).
if it continues to happen I'd follow up w/ support.