IP Address conflict on


Sometimes when I restart one of my Windows 10 computers the network never gets online. I have to disable/enable the network to get it back. the reason seems to be an IP conflict with the address This computer has a fixed IP, no DHCP is involved. The NIC is an Intel I219-V.



Event ID 4199, TCPIP: The system detected an address conflict for IP address with the system having network hardware address 20-4C-9E-49-38-8A.

A quick check in the tracking system revealed this article from Cisco: http://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/8021x/116529-problemsolution-product-00.html. It talks about a conflict between the IP conflict detection system in Windows and an ARP Probe sent by the switch as part of IP Device Tracking. I am no Cisco expert, but I would like to have a chat with whoever thought that IP conflict detection should start BEFORE the nic has an IP set…

As far as I can tell the IP Tracking function on the switch is enabled by default from IOS version 15.2.


Turn off IP Device Tracking at the switch

https://supportforums.cisco.com/discussion/11960461/ip-device-tracking talks about running the following commands on the switch:

switch(config)# int range gig1/0/1 – 24
switch(config-if)# nmsp attach suppress

This is supposed to turn off the IP Device tracking on a  per switch basis. I do not have access to my switching infrastructure, so I have not tested this. I will update this post if I get the opportunity to test it.

Turn off the Gratuitous ARP Function

Refer to this ancient KB: https://support.microsoft.com/en-us/kb/219374. It is written for NT4, but it still works. Be aware, this basically turns off IP Conflict detection completely.

Upgrade your NIC driver

And hope that it helps…

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