Intermittent incorrect DNS resolution?

Jay Ashworth jra at baylink.com
Thu Jan 17 00:16:57 UTC 2013


----- Original Message -----
> From: "Erik Levinson" <erik.levinson at 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 at 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



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