[Dnsmasq-discuss] problems with serving multiple networks, static assignments and default routes

Simon Kelley simon at thekelleys.org.uk
Mon Aug 9 13:47:57 BST 2010

Tim Allingham wrote:
> Hi All,
> I've currently got an issue with a dnsmasq config. the basic outline of
> the setup is
> 1) the server has 3 interfaces on separate networks,,
> 2) The server is configured with 3 dhcp-range declarations - one per
> network above, serving addresses in the 100-150 range of the subnets.
> 3) each subnet is assigned a tag - printers, async, sync.
> 4) based on the tag, a different gateway is being passed to the clients
> (not the interface of the dnsmasq server)
> 5) PC's all have a static assignment configured for them, along with the
> applicable network tag
> Basically the problem I'm running into is that the PC's aren't reliably
> assigned an address from their range, and almost never their static.
> One issue is potentially the fact that the 3 networks span the same
> hardware (ie common switchgear) but had expected the static assignments
> to alleviate potential problems from this.
> one config I have considered is setting up multple addresses on the one
> interface (ie eth0, eth0:0, eth0:1) and serving DHCP/DNS only from
> these, with the other 2 becoming solely upstream interfaces.
> I've attached the config, I'm hoping someone can shed some light on whether
> A) this is possible with dnsmasq (as far as I can see it shouldn't be an
> issue, I've done a similar thing across 2 networks previously)
> B) the physical layout is likely the issue
> C) where I'm going wrong in implementing this

If you set --log-dhcp, one of the things it logs is the available DHCP
address ranges for each transaction. That would be valuable information
in this case.



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