On Fri, Feb 04, 2022 at 09:28:42PM +0000, Simon Kelley wrote: > > > On 04/02/2022 18:16, Chris Green wrote: > > I'm looking at ways to provide backup DHCP/DNS with dnsmasq. This is > > on a small, fairly 'quiet' home LAN so there aren't dozens of clients > > connecting and disconnecting every second. Also if DHCP/DNS is not > > available for a few minutes the world won't end! :-) > > > > So, I'm proposing to have dnsmasq installed on two systems, one (say > > dns1, 192.168.1.2) is the live DHCP/DNS server, the other (say dns2, > > 192.168.1.3), both with static IP. > > > > If dns1 dies or needs to be turned off I just copy the dnsmasq > > configuration (stored elsewhere as well of course) to dns2 and also > > copy the dnsmasq.leases file and [re]start dnsmasq on dns2. Will this > > work reasonably OK? I.e. if/when a system on the LAN broadcasts a > > DHCP request will it get the same IP again? > > > > It's not a disaster if a system gets a different IP anyway, if > > something *really* needs a fixed IP I can add a dhcp-host in the > > dnsmasq configuration. > > > > I can even have dnsmasq running on dns2 all the time with it > > configured to provide only local DNS and no DHCP, then it's just 'copy > > dnsmasq configuration, copy dnsmasq.leases, restart dnsmasq. > > > > (All my systems run syncthing so it's very easy to have pretty much > > live copies of files synchronised across systems) > > > > To be honest, even if you didn't bother copying the leases file, most > systems would get the same address. The clients try to renew the lease on > the exiting DHCP server and when they get no response they broadcast the > renewal to try and find a new server. As long as there's no reason not to, > the new server will accept the client's request for the address it already > had. > OK, thanks Simon, I sort of knew this already but it's good to have it all confirmed.
-- Chris Green _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
