[Dnsmasq-discuss] two dnsmasq servers providing dhcp for one domain

Simon Kelley simon at thekelleys.org.uk
Thu Jul 16 16:17:21 BST 2009


Anand Kameswaran wrote:
> I am maintaining an internal private domain using dnsmasq.  However 
> there are n number of  subnets connected via infrastructure VPN, and up 
> until now I have had dnsmasq only on one subnet and it has been 
> succesfully serving DNS for all subnets.  However I now have a need to 
> add DHCP to those subnets.  Now I have succesfully setup dnsmasq to 
> serve DHCP to the subnet it is on.  However on the other side of the 
> VPN, obviously dhcp requests will not be recieved. 
> I was thinking I could setup a second dnsmasq instance on the other side 
> of the VPN, but then each DNSmasq will only know about the DHCP names 
> for the machines on it's side of the VPN.  I don't think DHCP relay is 
> an option (I could be wrong - but it is for a rather large number of 
> subnets)
> Is there a way to configure the two dnsmasq servers to update and/or 
> querry each other?  All machines on the subnets share the same domain, 
> so my understanding is that if dnsmasq doesn't find hostx.domain.com 
> <http://hostx.domain.com> then it will give up.
> 
> Currently the dnsmasq also do forward lookups for external addresses.
> 

Why do you dismiss DHCP relay? That seems to be the perfect solution in 
this case. Dnsmasq can handle lots of subnets without problem.

You need to have a machine on each subnet which can run the DHCP relay: 
it doesn't have to be the VPN router, though it can be.

http://www.thekelleys.org.uk/dhcp-helper/ or the ISC dhcp relay would do 
the job nicely.

I can't see any other way to achieve what you want easily.

Cheers,

Simon.



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