After enabling Windows Server 2012 R2 DHCP Failover, you will get the following error in log file:
36,<date>,<time>,Packet dropped because of Client ID hash mismatch or standby server…
According to the following technet article, this message does not indicate an error.
This event is only informational and can be safely ignored.
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.
The following article will help you to enable DHCP server log.
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