Re: dns based loadbalancing/failover

["E.B. Dreger" <eddy+public+spam () noc everquick net>]

> 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.

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