I am rather new to networking, and just landed a job as a net admin a few months back.
The company I'm working for is in a transitionary period, and we currently have 2 DHCP servers with 2 different scopes on 2 different subnets on the same LAN. The company has been running this configuration for at least 6 months. I know this is not recommended, but I also know that it can work...sometimes :) As you would expect, we have been experiencing the oddball intermittent problem here and there, but nothing too catastrophic.
Recently, we have been seeing some very strange behavior.
1.) IP address conflicts (approximately 5 per day) when we had maybe 1 per week previously which we traced back to a machine with a static assignment that did not have a reservation/exclusion in DHCP.
2.) When checking one server today, everything from xxx.xxx.xxx.3 to xxx.xxx.xxx.200 was showing as available (no lease, no reservation). A minute or two later, I attempted to reserve one of the available addresses and got a message that the address was in use. So I refreshed DHCP and lo and behold, AT LEAST 50 more addresses showed with leases. I know for a fact that there was no hardware failure, and that 50 people didn't suddenly turn on their machines.
Any ideas what would cause this sort of behavior (besides having 2 DHCP servers on the same LAN with two different subnets)?
My LAN has approximately 200 machines on the network at any given time spread across 3 buildings.
We rarely use static assignments - when we do, we make sure to add a reservation or exclusion for that address (excluding the 1 that was giving us problems previously).
Both servers and all main switches have had 100% uptime for 30 days.