[Dnsmasq-discuss] Web hang ups after repeated access to one site - dnsmasq related?

[Simon Kelley]

Chris G wrote:
> I recently (a few weeks ago) installed dnsmasq on my xubuntu 8.10
> system, it appears to work pretty well in general but a problem is
> appearing which *seems* to be related to when I started using dnsmasq.
> 
> What happens is that, occasionally, after accessing a particular web
> site many times, access to that web site hangs. All further access to
> the web site also results (eventually) in a time-out message. 

What is timing out? The DNS lookup or the HTTP transfer? The messages 
thatFirefox, at least, displays are fairly good at distinguishing these.

  This is
> not just one particular web site.  I first noticed it when searching
> for accomodation on various French web sites but today I got the same
> problem when hunting around www.broadbandbuyer.co.uk.
> 
> The problem is specific to my desktop machine (the xubuntu one) which
> is the one which is running dnsmasq.  When a web site is hung on my
> machine it's perfectly accessible from browsers on other machines on
> the same subnet/LAN and using the same router.  However IE within a
> virtual machine on my machine *can't* access the hung web site.
> 
> The last time this occurred I tried restarting dnsmasq and it seemed
> to fix the immediate problem, I got a few successful accesses to the
> web site that had stuck.  This is what leads me to believe I (maybe)
> have a dnsmasq problem.
> 
> My /etc/dnsmasq.conf file has only the following lines (apart from
> comments):- 
> 
>     domain-needed
>     bogus-priv
> 
>     expand-hosts
>     domain=isbd.net
>     dhcp-range=192.168.1.80,192.168.1.150,1h
> 
>     dhcp-option=3,192.168.1.1
> 
> 
> /etc/resolv.conf is:-
> 
>     nameserver 127.0.0.1
>     nameserver 195.74.113.58
>     nameserver 195.74.113.62
> 
> 
> That's about it, pretty standard dnsmaq installation.
> 
> Does anyone have any ideas what may be wrong, ways to diagnose it, or
> whatever? 
> 

Suggestions:

Use the dnsmasq log-queries option to see better what's going on.

Check that both the nameservers in /etc/resolv.conf are OK (try removing 
one at a time.) Resolvers on other machines will always try the first 
one first, dnsmasq will flit between them in a way which is note 
deterministic, but i tends to stick to the one it used last.

If the first nameserver is good, but the second is not, that would 
explain the problems you are seeing.


HTH


Simon.