[Dnsmasq-discuss] Questions about DHCP persistence and lease times
cl at isbd.net
Fri Sep 3 14:02:11 UTC 2021
On Fri, Sep 03, 2021 at 01:58:54PM +0100, Jesus M Diaz wrote:
> I wasn't considering erasing/deleting the dnsmasq.leases file, I was
> rather thinking of copying it to a non-running backup dnsmasq so
> if/when the running dnsmasq fails I can start the other and it will
> give out the same IPs.
> Do you really need this? I mean, if dhcp server dies and you have a
> stand-by backup that takes over immediately, the renew request from the
> hosts will be to use the same IP address, so if you don't have the
> dnsmasq.lease file, ergo there are no leases at the moment, dnsmasq
> would grant the same (requested) IP address.
That's why I asked the question about persistence of IP address, does
a client give a 'hint' to the DHCP server that it would like the same
IP again? However it's trivial to copy the contents of the leases
file across so it's not a big issue.
> The only other issue is then how to tell 'everyone' that the DNS
> server has
> changed address.
> Why don't you always include both DNS servers, so if one dies, the
> second one will be there anyway?
I was thinking about the usual "one local server and 126.96.36.199 or
188.8.131.52 as secondary" but now I think about it I suppose there's
nothing difficult about providing two local servers. However will
having one of them non-functional slow things down at all?
1 - How do I configure dnsmasq to give two DNS server addresses?
2 - Will only actually having one listening cause any delay?
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