[Dnsmasq-discuss] Not Resolving DHCP addresses

/dev/rob0 rob0 at gmx.co.uk
Thu Dec 24 00:37:24 GMT 2009


On Wed, Dec 23, 2009 at 04:01:19PM -0800, Andy Leak wrote:
> Now DHCP addresses are being resolved just fine, and everything
> is working 100% ok.
> 
> Here's what I did:
> - went to lunch
> - did a little christmas shopping
> - then came back and everything was working fine
> 
> Now I am curious why this problem occurred, and what happened to
> resolve the issue.  Any ideas??

Very simple: dnsmasq(8) can only serve names that are in its lists,
either hosts(5) or the leases file. If you start up a new dnsmasq on
an existing network, it has no magical means of knowing what leases
the previous DHCP daemon gave out. Over time, leases expired and your
hosts came in to renew them. Your dnsmasq didn't know these were
renewals.

> Thanks for DNSMASQ - it is really a great program.

Your shopping should have included a goodie for Simon! ;)

[the OP]
> I've got a new DNSMASQ installation.
> > - DHCP assigns addresses fine
> > - DNS resolution for external and fixed addresses is fine
> > - BUT - DNS resolution for DHCP addresses is not working
> >
> > Here's my dnsmasq.conf file...
> > domain-needed
> > domain=x
> > expand-hosts
> > resolv-file=/etc/resolv.conf.dnsmasq
> > dhcp-range=192.168.4.100,192.168.4.200,24h
> > local=/x/
> > log-queries
> > no-negcache
> > dhcp-authoritative
> >
> > when I do "nslookup xxx" (where xxx is the name of a dhcp 
> > machine) i get

nslookup(1) is buggy and not a good tool. I recommend that you become
familiar with host(1) and dig(1). All three are provided by BIND. The
ISC folks have threatened to drop nslookup.

> > ** server can't find xxx.x: NXDOMAIN
> >
> > when i look at the dnsmasq log, and the dnsmasq.leases file,
> > everything seems to be ok...

You looked, and at the time, "xxx" was in the lease file? I bet it
wasn't.
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