[PLUG] DNS weirdness

[Keith Lofstrom]

On Mon, Jul 21, 2008 at 10:35 PM, Keith Lofstrom <keithl at kl-ic.com> wrote:
> Another change that occured in the last two months was the change
> to Verizon FIOS and the addition of an Actiontec cable modem +
> router + etc.  That does a lot more than the old Linksys cable
> modem that I used for Comcast - among other things, it can act as a
> firewall, and adds another layer of NAT - so it may be part of the
> problem.

On Tue, Jul 22, 2008 at 2:30 PM, Ali Corbin <ali.corbin at gmail.com> wrote:
> > This sounds suspiciously familiar.  I sometimes have sporadic dns
> > resolution problems.
> > I've found that I can fix them by cycling power on my cable modem.
> > I'm not at home right now, so I can't be sure, but I think mine is
> > also an Actiontec.
> > Ali
> >

On Tue, Jul 22, 2008 at 02:42:27PM -0700, Ali Corbin wrote:
> I googled around for a bit, and found, at
>     http://www.broadbandreports.com/forum/remark,11430965
> 
> ----------------------------------------------------------------------------
> To the list, don't forget to add the DNS 1.0.0.0 problem.
> 
> For me, oddly, it has only manifested with "www" hostnames. In other
> words, I get 1.0.0.0 for "www.bob.com" but I get a good IP for
> bob.com.
> ----------------------------------------------------------------------------
> I used to have very frequent DNS 1.0.0.0 problems. For me at least,
> the solution was to put the ISP DNS host IP addresses in the NIC IP
> settings (static DNS) on the computer to which the Actiontec is
> connected via ethernet. If the DNS info is left as dynamic, I am
> guaranteed to see frequent 1.0.0.0 errors. Qwest DSL support was no
> help in figuring this out. They had never heard of the 1.0.0.0
> problem.
> -------------------------------------------------------------------------------

Interesting pointer, but that does not seem to be my problem - I am
running my own domain server, not an outside one, and I am starting
with "hints" from the root name servers.  The problem is that some
of the DNS requests do not appear to get answered.

I found this:
   http://aplawrence.com/MacOSX/dns_puzzle.html

And that may be a fruitful path to explore.  The author says that
the Actiontec is truncating UDP packets longer than 512 bytes,
which can cause a fallback to TCP.  However, some DNS servers do
not support DNS queries on TCP.  More experimentation needed.
The author points at:

http://www.dslreports.com/forum/r17679150-Howto-make-ActionTec-MI424WR-a-network-bridge

Which is how to turn the Actiontec into a bridge.  Personally, I 
would rather get rid of the damned thing entirely and connect through
the CAT5 that I ran to the other side of the wall from the ONT.
That way I will not be burning power in it.

Alternately, I will learn how to configure named.conf so DNS
pulls name service from my offsite server for outside addresses.
Or something ...

Keith

-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs