[Dnsmasq-discuss] dnsmasq for road warriors

/dev/rob0 rob0 at gmx.co.uk
Sun Nov 11 23:05:54 GMT 2012


> On 10/11/2012 15:54, /dev/rob0 wrote:
> >Seems to me that dnsmasq is a better nscd replacement, and
> >it has a place in mobile computing.
> >
> ># we use this dnsmasq as this system's own resolver
> >no-resolv

On Sat, Nov 10, 2012 at 05:46:10PM -0600,
   richardvoigt at gmail.com wrote:
> no-resolv is doing more harm than good.
>
> dnsmasq is smart enough to ignore 127.0.0.1 in /etc/resolv.conf
> And it will automatically pick up DHCP-assigned DNS servers which
> written there.

But you don't understand. The point of dnsmasq on a laptop is to 
serve ONLY that machine and its local processes. /etc/resolv.conf 
must contain ONLY "nameserver 127.0.0.1". If there are other 
nameservers listed, the system resolver will be contacting them;
possibly getting different results, and ... well, this discussion 
would not be relevant to the dnsmasq list.

> Some DHCP clients have an option to update a different file with 
> the DNS servers, in that case use dnsmasq's resolv-file option.

Either this, or DHCP hooks as Ed mentioned, is the way to go. 
Actually DHCP hooks are needed in either case, as dnsmasq must be 
signalled to reread its configuration (I guess that means stop and 
restart, which is sad because it loses the cache.)

On Sun, Nov 11, 2012 at 08:34:38PM +0000, Ed W wrote:
> Try:
>     http://roy.marples.name/projects/openresolv

Eww, no. That's a kludge, and again, it totally misses the point of 
this dnsmasq instance exclusively providing DNS to local processes. 
This was brought to the dnsmasq mailing list for a reason: I am 
indeed using dnsmasq.

> >Speaking of cruft, maybe that's not a bad thing? What will
> >dnsmasq do with multiple upstream servers?
> >
> >server=192.168.40.1
> >server=192.168.0.1
> >server=192.168.1.1
> >server=8.8.4.4
> >
> >When we're at a site where one of those is our router, that
> >should respond much faster than 8.8.4.4 can. OTOH, it could
> >cause intermittent errors with local names; 8.8.4.4 is not
> >going to know "minipax.rob0.lan".
> >
> >Can we priortise upstream servers? --all-servers implies that
> >this can be done somehow, but I don't know how ... is it merely 
> >the order in which they are listed in the config (or on the
> >command line)? When not using --all-servers, how does dnsmasq
> >decide when to try a different one, and which one will be tried
> >in that case? Random selection, rotating sequential, fixed 
> >top-down priority?
> >
> Nothing wrong with dhcp hooks.  Setup things as advanced as you 
> need. Dnsmasq regularly sends *all* requests to *all* nameservers 
> and picks the fastest responding.  So it will choose a faster 
> responding server where there are several options

This goes against what the manual says. See "--all-servers" in the 
man page. What you describe is only applicable when "--all-servers" 
was specified. I don't think I would want that.
-- 
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