[dns-operations] EDNS issue

Mark Andrews marka at isc.org
Fri Feb 25 11:59:32 UTC 2011

In message <15A36D24D8F44607A9C047E7D7894AC0 at local>, "George Barwood" writes:
> ----- Original Message ----- 
> From: "Mark Andrews" <marka at isc.org>
> To: <frnkblk at iname.com>
> Cc: <dns-operations at dns-oarc.net>
> Sent: Friday, February 25, 2011 1:26 AM
> Subject: Re: [dns-operations] EDNS issue
> > 
> > In message <006d01cbd482$d54e5a30$7feb0e90$@iname.com>, "Frank Bulk" writes:
> >> Our ISP helpdesk has been receiving a lot of complaints about their
> >> inability to check the weather weather.gov, specifically,
> >> forecast.weather.gov.  Some digs showed that queries were failing, and my
> >> BIND logs show the same:
> > 
> > Make sure you can receive fragmented UDP responses.  The servers
> > are sending good reponses.
> Can you clarify why end users were complaining?
> Doesn't BIND time out quickly enough if fragmented packets get lost?
> I was under the impression that the result would be reduced performance
> rather than failure.

It takes time to detect that a reply has been blocked and when you
have a CNAME chain and you need to go through the process a second
time the client sometimes times out.

There is only so much you can do in 2-3 seconds and most of that
is limited by the speed of light.

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org

More information about the dns-operations mailing list