I was recently reminded of an issue we had with our small office LAN.  Periodically, the small server we had serving basic network services like DHCP and DNS would crawl to a halt or crash.  Upon investigation, I discovered it was due to the system running out of memory.  After rebooting, the system seemed to run just fine.

To help diagnose, I added NSClient++ to the system and monitored system resources via Nagios.  Sure enough, over time you could see the memory usage slowly increase.  I discovered it was the DHCP server process causing the issue.  A little googling led me to the "A Windows Server 2008-based DHCP server that is configured in a workgroup environment may consume too much memory" Microsoft KB article.

Sure enough, after performing the suggested registry change we have not seem the same memory utilization issue that lead to the server crashing.  To spoil the lovely KB article, you just need to execute the following command (one-line):

reg add HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\DHCPServer\Parameters 
/v DisableRogueDetection /t REG_DWORD /d 1