Nagios Support Forum

How to monitor Physical server Commissioning/De-commissioning ?

What exactly are you looking to monitor in this respect? There could be a multitude of things to check, of course when a server goes down, so does it's network connection, so you could make a check as simple as pining it's address, though it won't tell you much as the server could go down for decommissioning, or for another reason, but then again if it was going down you would loose any way to check against it unless it was managed by another piece of software you could check against.

Are you trying to add and remove configs on the fly (for elastic environments)?

Yes.
When server installed & configured in Nagios for monitoring, I assume it is stage of server commissioning & when server removed from production environment after specific period, comes in De-commissioning.

What are you looking to monitor in this respect? As was already stated this is a manual sort of thing, you could add a note to the host that will show you when a server is going to be decommissioned, then, if it goes down, and it is on that date you could remove it. Otherwise, you may want to look at building a custom component which would allow you to log commission dates, and then from the pool of hosts, remove certain ones when the time comes.