[159634] in North American Network Operators' Group
Re: Intermittent incorrect DNS resolution?
daemon@ATHENA.MIT.EDU (Jay Ashworth)
Wed Jan 16 19:17:09 2013
Date: Wed, 16 Jan 2013 19:16:57 -0500 (EST)
From: Jay Ashworth <jra@baylink.com>
To: NANOG <nanog@nanog.org>
In-Reply-To: <50F722FD.7010201@uberflip.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
----- Original Message -----
> From: "Erik Levinson" <erik.levinson@uberflip.com>
> I'm having an unusual DNS problem and would appreciate feedback.
>
> For the zones in question, primary DNS is provided by GoDaddy and
> secondary DNS by DNS Made Easy. Over a week ago we made changes to
> several A records (including wildcards on two different zones), all
> already having a TTL no greater than one hour.
>
> The new IPs on those A records have taken many millions of requests
> since the changes. Occasionally, a small amount of traffic appears at
> the old IPs that those A records had. This is HTTP traffic. Packet
> captures of this traffic show various Host headers.
I'm a touch surprised to find that no one has mentioned the facet of
Windows OSs that requires "ipconfig /flushdns" in some such circumstances...
Not only may *browsers* be caching DNS lookups without regard to TTLs,
the *OS* might be doing it to you too, in circumstances I was never quite
able to get a handle on.
XP was known to do this, as late as SP3; I'm not sure about V or 7.
Cheers,
-- jra
--
Jay R. Ashworth Baylink jra@baylink.com
Designer The Things I Think RFC 2100
Ashworth & Associates http://baylink.pitas.com 2000 Land Rover DII
St Petersburg FL USA #natog +1 727 647 1274
