[ubuntu-uk] DNS settings resetting

[Colin Law]

2010/1/15 Dave Morley <davmor2 at davmor2.co.uk>:
> On Fri, 2010-01-15 at 11:38 +0000, Colin Law wrote:
>> 2010/1/15 Dave Morley <davmor2 at davmor2.co.uk>:
>> > On Fri, 2010-01-15 at 11:19 +0000, Colin Law wrote:
>> >> I am using Ubuntu 9.10 wired to a Linksys modem/router using DHCP to
>> >> get IP etc.  All works fine normally and if I right click on the
>> >> connection icon in the top panel and select Connection Information I
>> >> see my IP address etc as expected, including Primary and Secondary DNS
>> >> servers as provided by my ISP.
>> >>
>> >> Occasionally, however, once a day or so, the DNS values get set to
>> >> 192.168.1.1 (the router ip) and dns fails of course.  If I unplug my
>> >> ethernet cable for a few seconds and plug it back in then it picks up
>> >> the dns again and all is well.
>> >>
>> ....
>>
> Okay two things you can try.
> 1: find the reset button on the router, factory reset it then set it
> backup (this can be annoying)

I am somewhat loathe to do that, I think there is always some risk in
an operation like that.  I would prefer to convince myself that it is
worthwhile before trying this.  It seems a rather odd sort of fault in
the router just sometimes providing the wrong data but working
correctly the rest of the time.

Are DHCP requests logged anywhere on the PC?

I wonder what would be the result if the renew request failed
completely, would the PC possibly keep its IP address but reset the
DNS?   Again it would be useful if I could get DHCP requests logged
somehow.

> 2: Right click n-m applet and select edit connections, highlight the
> connection you wish to edit, go to ipv4 settings tab select auto (dhcp)
> address only and drop the ip address of your dns server into the dns
> tab.

I see that this should solve the problem, but I would prefer to
understand what is going on and fix the root cause of the problem if
possible.  Not that I am not grateful for the suggestion however.  A
disadvantage of this is that I occasionally connect the laptop to a
router in a different locality, and the DNS settings would be
different there.

Thanks again for the suggestions

Colin