I recently acquired a client that has a strange ARP caching issue on one of thier servers.

I have a server that will eventually start turning it's dynamic ARP entries into static ARP entries. This causes problems because when the machine that has a static ARP entries on this server receives a new IP via DHCP, then the server is not able to communicate with the clients. Clearing the ARP cache resolves the issue and the server is fine for about a week and then it starts slowly turning ARP entries into static ARP entries. I haven't narrowed it down to when or how many it starts to do, but slowly you start seeing 1 static ARP and then 5 and then 10.

The server in question is a Windows Server 2003 SP2. It is a DC, DHCP, and DNS server. I've checked the DHCP scope options and there's nothing in there that would indicate anything to do with static ARP entries. The only thing different between this DNS server and our other DNS server is that the 'Dynamically Update DNA A and PTR records for DHCP clients that do not request updates' is checked on the problematic server.

I've done a bit of research about this and it seems that this may happen if any PXE type services are running, from what I can tell, there is nothing running a PXE server.

I'm a bit lost as I have never seen dynamic ARP entries start to turn into static ARP entries. Right now my solution is a schedule task that runs every 24 hours to clear the ARP cache (arp -d *). I would like to not rely on this schedule task.

Has anybody seen this before or have any suggestions on how to troubleshoot this?