[43347] in North American Network Operators' Group
Re: dns based loadbalancing/failover
daemon@ATHENA.MIT.EDU (E.B. Dreger)
Sat Oct 6 14:23:14 2001
Date: Sat, 6 Oct 2001 18:22:34 +0000 (GMT)
From: "E.B. Dreger" <eddy+public+spam@noc.everquick.net>
To: bert hubert <ahu@ds9a.nl>
Cc: nanog@merit.edu
In-Reply-To: <20011006191739.A29891@outpost.ds9a.nl>
Message-ID: <Pine.LNX.4.20.0110061817550.7868-100000@www.everquick.net>
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> Date: Sat, 6 Oct 2001 19:17:39 +0200
> From: bert hubert <ahu@ds9a.nl>
(top-posting due to length of original post)
Alas, the "after your TTL expires" is a killer. I don't want to
resurrect a thread that has been covered in the past couple of
months, but DNS just doesn't cut it for failover. Furthermore,
fast DNS response != fast HTTP response.
{Swamp space|non-Verio filtering policies} and BGP are the way to
approach this. For redundant DNS at a single site, IP and MAC
takeover are what one wants.
All IMHO.
Eddy
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> The really neat thing is that you can do this with any nameserver. Install
> N nameservers and connect each of them to one of your ISPs. These
> nameservers are all masters, and all contain different data.
>
> Each one responds with data relevant for the IP addresses of that ISP. If
> all your links are up, people will get mixed responses. If one ISP is down,
> that nameserver will stop answering, and hence after your TTL expires, no
> requests will be made for those IP addresses.
>
> It gets even better - recursing nameservers have the habit of locking in to
> nameservers that respond quickest. So you even get some loadbalancing
> awareness.
>
> We operate nameservers in the US and in Europe, and we definitely see this
> effect.
Date: Mon, 21 May 2001 11:23:58 +0000 (GMT)
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