one-lease-per-client... seriously

Simon Hobson dhcp1 at
Fri Sep 16 07:00:15 UTC 2016

On 15 Sep 2016, at 21:00, Brian Rak <brak at> wrote:

> I'm running into an issue where DHCPD (v4.3.4 and older versions) is issuing multiple leases to the same mac address.  It appears to be looking at the DHCP Client-ID field to determine what a unique client is.

That is by design as is **REQUIRED** by the RFCs.
It's a long standing problem that some real-world situations clash with this - most notably when there is multi-boot with Windoze and anything else since Windows defaults to using the MAC address as client-id and everything else defaults to not sending one. But that's what the standards require and the ISC implementation has always been intended to be a "reference" implementation that completely meets the standards as laid down (unlike several other servers which really do break the rules a lot).

>  I'd much rather it ignore everything except for the client's mac address, but I can't seem to find an option to do this.

It used to require patches, but I see Jeff has suggested an option to deal with this.

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