DNS Failover

Pete Tenereillo pt_bind at hotmail.com
Thu Oct 14 12:59:40 UTC 2004

Anthony mentioned he has a Web app, so that TTL trick won't work reliably. 
The low TTL would be seen by servers "throughout the rest of the world" but 
TTL are ignored by most clients (and many proxy servers), so all existing 
users (and users that share such proxies) will be stuck on the downed 
server. Check out:


for details. IMO for failover you are better off putting both servers at the 
same site, using local load balancing (there are some very cost effective 
solutions available now) and redundant power and Internet connections.


----- Original Message ----- 
From: "Greg Maccarone" <gmaccarone at gmail.com>
To: "Anthony Wilkins" <anthony_wlkns at yahoo.com>
Cc: <comp-protocols-dns-bind at isc.org>
Sent: Tuesday, October 12, 2004 11:46 AM
Subject: Re: DNS Failover

> On Tue, 12 Oct 2004 11:01:45 +0200, Anthony Wilkins
> <anthony_wlkns at yahoo.com> wrote:
>> Hi, is there anybody who can help me in finding a solution to a problem
>> I have?
>> My web server is sometime temporarily down and I want people to go to my
>> remote site where I have a backup web server. Can I change DNS on the
>> Internet fast enough for incoming requests to be handled by my redundant
>> web server? Normally I don't want traffic to go to the remote site.
>> Thanks, Anthony W.
> A way this could be achieved with DNS is to have a low TTL on the host
> entry that could be changing because of the outage.  Then in most
> cases it would take no longer than the specified TTL for the changes
> to be seen throughout the rest of the world.
> my $.02.
> -- 
> Greg Maccarone
> gmaccarone at gmail.com

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