Server with static IP acquiring DHCP
I'm seeing strange behaviour on a Windows Server 2008 R2 Enterprise server (physical box). It has a static IPv4 address which it happily talks out over, and services such as RDP respond on that static IP. However, the A record for that server in DNS is being updated with a different IP address, which is causing havoc for installed services. The IP address is on a DHCP range. I've checked on the DHCP server and that address lease is definitely in there, against the physical MAC address of the server. Within the server GUI, there is no record of the DHCP address - not in the registry, ipconfig, nothing. I've run the following tests: plugged the server into a different port on the switch erased the lease and restarted the DHCP server removed the server from AD (it's currently running in workgroup mode) changed the networking on the server to DHCP, verified that it was talking on the DHCP address, and then changed it back to static In every instance, the dynamic lease was reassigned. The server has a single onboard NIC, which is an Intel 92567LF-2 adapter running the Intel driver (version 10.1.6.0, date 20/10/2009). This is bizarre behaviour - has anyone seen this before? UPDATE - I've noticed that if you ping the dynamic address from any other machine, it responds, and then if you check the arp cache there is an entry for both the dynamic and the static IP against the same MAC address. But, I can't ping the dynamic address from the server.
April 14th, 2010 2:27am

Yeah.. I had something similar and tracked it down by auditing the A record and discovering who was updating it. In my case the DHCP scope was set to always update A record even if not requested by host. Becuase my box initially had a DHCP address the DHCP server was continually updating DNS. Of course this would have resolved itself after the lease expired. Mick Huxley
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April 14th, 2010 3:08am

Thanks for the info Mick. That almost mirrors what I'm seeing, but since removing the server from AD, the A record no longer exists and isn't being recreated, although the DHCP lease is still being handed out....
April 14th, 2010 3:24am

i've seen similar issues with older realtek onboard nics - have you installed the intel driver suite? sometimes there is an oddness around the MAC that is assigned - check on the dhcp server if the mac matches.see if an ipconfig /registerdns helps at allother than that i would suggest cracking open network monitor or wireshark and what's happening on the wire when this goes on.
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April 15th, 2010 5:11am

Thanks jorke - I don't have the full driver suite installed, but will do so. The machine is currently offsite so I'm bringing it onsite within the next 24 hours and will update BIOS, driver suite and will run a wireshark trace to find out what's going on.
April 15th, 2010 10:01am

Looks like it was the Intel Management Engine. I noticed in DHCP that the dynamic address was being assigned by the DHCP server before the OS had even started to load. Disabled IME (don't need it on this system) and the dynamic lease ceased to be allocated.
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April 16th, 2010 8:11am

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