[Dnsmasq-discuss] help needed in dnsmasq problem

Atul Gupta atul14.kumar at gmail.com
Thu May 17 20:55:41 BST 2012


Hi Richard,
I Got it. But in this case dnsmasq is ignoring 192.168.160.20 which is
a upstream server. It is present in config file but dnsmasq never uses
it for querying irrespective of number of queries i send or time has
passed, it only keep trying 2001:5b0:3eff:fff7::20.

I also observed that if your DNS servers are having a problem, the
dnsmasq fails to resolve DNS (expected), then it seems like the
dnsmasq calls the DNS Server address "bad" and never tries them again,
because i  had a DNS server problem ...resolved it ...yet the dnsmasq
never could do DNS resolution after the DNS server problem was
resolved.

On Thu, May 17, 2012 at 2:38 PM, richardvoigt at gmail.com
<richardvoigt at gmail.com> wrote:
> It's not anything specifically wrong in the configuration file, but it
> doesn't sound like it matches your network setup.
>
> From your question, I think you have some names that can only be
> resolved by one of your nameservers?  And therefore you are concerned
> when dnsmasq doesn't contact the server with the ability to resolve
> those names.
>
> But dnsmasq's list of upstream servers is designed for redundancy, and
> it requires that any query can be sent to any arbitrary server and get
> a correct answer.  There is not load balancing per se, but checks are
> done to see which server on the list is the nearest/fastest, which
> will tend to pick the least busy server, which is similar to load
> balancing.
>
> If some queries must be sent to a single server, then you should
> create per-domain rules that cause those queries to go to that server,
> and not be handled by the global upstream.
>
> "strict-order" will help determine if this is actually your problem,
> because it causes queries to be sent to every server in turn.  But it
> hurts performance, so adding domain-specific server entries is the
> better way.
>
> On Thu, May 17, 2012 at 11:32 AM, Atul Gupta <atul14.kumar at gmail.com> wrote:
>> Please reply what you think is not correct in conf file.
>>
>> Thanks.
>>
>> On Thu, May 17, 2012 at 12:29 PM, richardvoigt at gmail.com
>> <richardvoigt at gmail.com> wrote:
>>> I think your configuration is wrong, but as a test, does the
>>> "strict-order" option fix your problem?
>>>
>>> On Thu, May 17, 2012 at 9:38 AM, Atul Gupta <atul14.kumar at gmail.com> wrote:
>>>> Hi,
>>>> One server in my dnsmasq.conf file is never tried for sending the query.
>>>>
>>>>   Below is my config file:-
>>>>   # Management DNS servers [2]
>>>>   server=/ody.engr.net/2001:5b0:ffff:fff6::25 at 2001:05b0:3efe:2e1f:0000:0000:004c:4d0d
>>>>   server=/ody.engr.net/2001:5b0:ffff:fff6::26 at 2001:05b0:3efe:2e1f:0000:0000:004c:4d0d
>>>>   address=/controlcenter.com/192.168.0.1
>>>>   address=/controlcenter.com/fd0d:edc3:e12a:0000::1
>>>>   address=/www.odyagentid.com/66.82.162.22
>>>>   cache-size=1000
>>>>   max-ttl=60
>>>>   neg-ttl=60
>>>>   no-resolv
>>>>   max-ipperhost=5
>>>>   server=192.168.160.20 at 172.20.54.1
>>>>   server=192.168.160.20 at 172.20.54.1
>>>>   server=2001:5b0:3eff:fff7::20 at 2001:05b0:3e1a:8000:0280:aeff:fe4b:0277
>>>>   server=2001:5b0:3eff:fff7::20 at 2001:05b0:3e1a:8000:0280:aeff:fe4b:0277
>>>>   I guess dnsmasq adds all servers in the daemon->servers list and picks
>>>>   servers from there while forwarding the query. My question is that if
>>>>   there is any scenario where dnsmasq removes any server from this
>>>>   (daemon->servers) list.As this is what seems to happening in my case
>>>>   i.e. server 192.168.160.20 is never being tried to forward the query.
>>>>   restart of dnsmasq solves this problem.
>>>>   Also when this problem comes and dump cache, there is no entry for
>>>>   192.168.160.20. below is dump
>>>>
>>>>   cache size 1000, cache insertions 2644, re-used unexpired cache entries 0
>>>>   queries forwarded 1301, queries answered locally 37
>>>>   server 2001:5b0:ffff:fff6::25#53: queries sent 0, retried or failed 0, used 0
>>>>   server 2001:5b0:ffff:fff6::26#53: queries sent 0, retried or failed 0, used 0
>>>>   server 2001:5b0:3eff:fff7::20#53: queries sent 680, retried or
>>>> failed 0, used 0
>>>>   Host                                     Address
>>>>    Flags     Expires
>>>>
>>>>   Please ignore the counters next to  "queries sent", "cache insertions"
>>>>   etc. as they may be inconsistent, but real problem is that i don't see
>>>>   192.168.160.20 in this list.
>>>>
>>>>   Please help!!!!
>>>>   Regards,
>>>>   Atul.
>>>>
>>>> _______________________________________________
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>>>> Dnsmasq-discuss at lists.thekelleys.org.uk
>>>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss



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