[Dnsmasq-discuss] DHCP multi tenancy

[Nicolas Cavallari]

On 18/08/2025 13:49, Kevin wrote:
> Hello
> 
> We need to implement multi tenancy at the DHCP level. It means the same subnet (e.g 10.0.0.0/24) might be used by several clients and both should be able to get a lease for 10.0.0.1.
> 
> We planned to implement this by relying on the Circuit-Id to help us distinguish which subnet to choose from.
> 
> Unfortunately, we did not manage to make it work. Can you confirm this feature (reusing the same subnet several times) is not currently possible?

Not the maintainer, but dnsmasq only has a single DHCP lease database (a 
single IP -> client mapping). What you want is to have several of them, 
which is not possible with a single instance of dnsmasq.

The circuit-id in the DHCP relay agent information option isn't designed 
for that either. It's primary purpose is to help a dumb DHCP relay to 
forward the response from the server to the correct downtream interface 
in cases the downstream interfaces do not have their own routable IP 
addresses. Using it to select distinct DHCP databases on a server is 
really not what the RFC intended, you better know what you are doing.