[Dnsmasq-discuss] Single interface, multiple subnets...

Scott vivosomnio at comcast.net
Mon Sep 27 17:55:13 BST 2010

The DHCP relay is the router itself, ip helper is configured which forwards
the packets.  Again, the dhcp requests are being received by the dhcp
server, it simply won't serve out the address.  One thing I did forget to
mention is that I have mac reservations for each server.

The issue however, is not in the routing.  If I take server1 and modify the
reservation to an IP in the dhcp server's subnet (, the
dhcp server gives it an address.  It's only when I tell the dhcp server to
give it an IP in the subnet that it gives the error:  "Sep 24
12:45:47 server1 dnsmasq[2640]: no address range available for DHCP request
via eth0".

-----Original Message-----
From: Simon Kelley [mailto:simon at thekelleys.org.uk] 
Sent: Monday, September 27, 2010 3:40 AM
To: Scott
Cc: dnsmasq-discuss at lists.thekelleys.org.uk
Subject: Re: [Dnsmasq-discuss] Single interface, multiple subnets...

Scott wrote:
> Well, what I'm doing is simply trying to have DHCP IP's for 2 
> different subnets ( and served out of 
> a single interface.  The machines are on 2 different physical network 
> segments.  The
> has a default gateway of, the 
> subnet has a default gateway of  
> Routing is set so that the DHCP request will route to the DHCP server.  
> I turn on server 1 & server 2, and though both DHCP ranges are set, 
> and the DHCP Request packets from both servers are received by the 
> DHCP server, it only serves out a DHCP address for server 2, and for 
> server 1 (the server which is on a different subnet & network segment) 
> gives the error I indicated below: "Sep 24 12:45:47 server1
> dnsmasq[2640]: no address range available for DHCP request via eth0".

How are packets routed from the network segment containing server1 to the
DHCP server? If it's a different physical segment  then it will be in a
different broadcast domain and DHCP broadcasts from that segment won't ever
make it to the server. Clearly they are, so there's something more complex
happening, but you're not telling us what. The solution to this problem is
almost certainly to use a DHCP-relay, but exactly how that should be done
depends on the details of your routing.



More information about the Dnsmasq-discuss mailing list