bug in DHCP client and/or DHCP server implementation

[Ted Lemon]

When one member of a failover pair NAKs an IP address assigned by the 
other, it is a sure sign that the two servers are not compatibly 
configured.   The configurations on the two servers should be 
_identical_ except for failover, unless you really, really know what 
you are doing.

As for your commentary on how the protocol goes, that is how the 
protocol goes.   The reasons why it works this way are well documented, 
both in the RFC and in the DHCP Handbook.   :'/

This is really a line of discussion for dhcp-server at isc.org, not 
dhcp-hackers at isc.org.