bind update on xx.xx.xx.xx from <peername> rejected: incoming update is less critical than outgoing update

Question:

I'm seeing this error being logged:

bind update on xx.xx.xx.xx from <peername> rejected: incoming update is less critical than outgoing update

What does it mean?

Answer:

What's happening is the local server is sending a binding update, and has received a binding update before receiving an ack on its own update (so it is still pending).

In this situation, the server doesn't want to ack the peer's update because then the peer will receive that ack after the local server's update - so it has to reject or nak the binding update to clear it from the peer's queue.

If dhcpd gets a rejected update, it always logs the reason, but these particular error reports can be ignored.

If you're seeing this on every single binding update, then it's likely that they're being caused by an odd or incorrect configuration.