[Dnsmasq-discuss] dnsmasq with high availability and dynamic range

[Simon Kelley]

There's no specific HA support in dnsmasq.

If you're not concerned about populating the DNS side with IP addresses 
assigned via DHCP, the simplest way to do this is to split the dynamic 
IP address range in two, and give half to each instance, with long lease 
times.

That way a new client can always get an address even if one instance is 
down, and you have half the lease time to fix a failed instance before 
clients start failing to renew and change IP address.


Simon


On 11.02.2026 16:06, Goswin von Brederlow wrote:
> Hi,
> 
> 
> I've been using dnsmasq running on 2 headnodes for a cluster with high 
> availability for some time with static dhcp-host entries. So far this 
> runs in an active/active setup, meaning dnsmasq runs on both headnodes 
> all the time. Hosts then get answers from both servers but since the IPs 
> are assigned based on the MAC using the same config there never has been 
> any conflict between the two dnsmasq instances.
> 
> 
> Now I'm adding a dynamic range to the setup for hosts that haven't been 
> registered yet and there I forsee problems if both servers assign the 
> same IP to different hosts.
> 
> 
> Is there some support in dnsmasq for HA that I'm not seeing where the 2 
> instances of dnsmasq would coordinate their leases in some way that I'm 
> not seeing? Or should I simply split the dynamic IP range between the 
> servers so they don't overlap? Are there other options or 
> recommendations for a high availability setup for dnsmasq?
> 
> 
> MfG
> 
> Goswin
> 
> 
> 
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