[155631] in North American Network Operators' Group
Re: Return two locations or low TTL [was: DNS caches that support
daemon@ATHENA.MIT.EDU (Patrick W. Gilmore)
Mon Aug 20 14:30:16 2012
From: "Patrick W. Gilmore" <patrick@ianai.net>
In-Reply-To: <2A87A6F7-877F-4BA0-8FCF-24BC486ED1F7@arbor.net>
Date: Mon, 20 Aug 2012 14:29:38 -0400
To: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Aug 20, 2012, at 10:07 , "Dobbins, Roland" <rdobbins@arbor.net> =
wrote:
> On Aug 20, 2012, at 5:56 PM, Patrick W. Gilmore wrote:
>=20
>> My question above is asking Mark how you guarantee the =
user/application selects the A record closest to them and only use the =
other A record when the closer one is unavailable.
>=20
> I understand - my point was that folks using a GSLB-type solution =
would generally include availability probing in the GSLB stack, so that =
a given instance won't be included in answers if it's locally =
unavailable
How does that allow for a long TTL? If you set a 3600 second TTL when =
the DC is up, and the DC goes down 2 seconds later, what do you do?
> (obviously, the GSLB can't know about all path elements between the =
querying resolver and the desired server/service).
Says who? :)
--=20
TTFN,
patrick
