[Dnsmasq-discuss] DNS from dhcp-host while client is offline

Michael michael at kmaclub.com
Tue Oct 5 12:43:26 UTC 2021

On 10/4/21 05:37, Dominik Derigs wrote:
> Hey Petr,
> On Mon, 2021-10-04 at 11:45 +0200, Petr Menšík wrote:
>> Perhaps a flag could be added to dhcp-range, requesting also
>> addition of dhcp-hosts to static dns.
> Maybe this flag would better be set on --dhcp-host and --dhcp-
> hostsfile if this is used? This would feel more "natural" to me.
> Initially, I've myself found this an odd behavior to only serve
> only DHCP host names that are known to be "alive". I do see some
> value in not serving A records when we know the server is
> offline, however, the very same happens on the Internet all the
> time: no DNS server I'm aware of checks if an A record is
> reachable before giving you the reply.
> I've seen other systems using dnsmasq (it may or not have been
> DD-WRT, no promises!) that created two files from static leases:
> A dhcp-hostsfile and an addn-hosts file. Having an option to make
> the latter obsolete sounds like a good idea.

Maybe I am misunderstanding the issue, but dnsmasq already give the 
ability that is being asked for I believe.

If you want a static DNS entry, add the entry to /etc/hosts or -addn-hosts=

If you want a DHCP lease that always hands out the same ip address but 
is only valid during the lease, create a dhcp-host entry that includes 
the IP & hostname

If you want a DHCP lease can always be looked up via DNS, add it to 
/etc/hosts or -addn-hosts and the dhcp-host entry contains the hostname


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