After enabling Windows Server 2012 R2 DHCP Failover Getting Packet dropped because of Client ID hash mismatch

Question

_{Friday, April 24, 2015 4:04 PM}

We have two DHCP servers at our site (they are each located on different subnets).  These DHCP servers are running Windows Server 2012 R2.  They are dedicated DHCP servers.  Yesterday afternoon, we reconfigured several scopes such that they could become members of the single DHCP Failover Relationship we have configured as Load Balance with 50% of the load placed on each DHCP Failover Relationship member (DHCP Server).

However, this morning, users reported that they were unable to renew their DHCP addresses.  Looking into the DHCP logs on both DHCP servers, there are several entries that are as follow:

"36,MM/DD/YYYY,HH:MM:SS,Packet dropped because of Client ID hash mismatch or standby server.,IP subnet,,MAC Address,,0,6,,,,,,,,,0"

I performed a manual synchronization of the Failover relationship and all scopes on both DHCP servers.  I also restarted the DHCP service on both DHCP servers but we are still getting the same error.

A Bing/Google search did not bring any light to the issue we are encountering.  Has anyone encountered this and if so, what is the solution.

I should add that when I initially attempted to perform an ipconfig/renew on my workstation, it failed and the error listed above showed up in the DHCP log of only one of our DHCP servers but not the other.  However, once I performed an ipconfig /release and then an ipconfig /renew, I was able to renew my lease.

I should also add that the DHCP Server event logs on both DHCP servers are clean, there are no warnings and/or errors reported.

All replies (1)

_{Friday, April 24, 2015 5:02 PM ✅Answered}

Well, according to this article (https://technet.microsoft.com/en-us/library/dn338988.aspx?f=255&MSPPError=-2147217396), this can be safely ignored. A DHCP-failover informational event that is commonly recorded in the DHCP Audit Log is event ID 36: 36,<date>,<time>,Packet dropped because of Client ID hash mismatch or standby server… This event is only informational and can be safely ignored. It does not indicate an error. In DHCP failover, the client messages which are broadcast are received by both the DHCP failover servers. However, only one server responds to the client messages. In case of load balance mode, the servers will hash the MAC address of a DHCP client to establish which of them must respond. In hot standby mode, only the active server responds. In both cases, the DHCP server which does not respond to the client logs this message in the audit log. </time></date>