High-Availability on the network level

[Tom Brown]

On Sun, 3 Feb 2002, Alex Kramarov wrote:

> Hi.
> 
> While usually this list receives question of high-availability regarging
> redundant server configurations, i would like to ask about something else :
> after i made sure i have redundant server config, how do i make sure they
> will always be accessible from the internet by the same dns name, providing
> i have 2 of more different internet connections, without using BGP ?
> 
> let's assume, that i have 2 ip ranges from my isp providers, 1.1.1.1/24 and
> 2.2.2.2/24, and the active server will always be accessible by 1.1.1.10 and
> 2.2.2.10. what when the 1.1.1.1 provider is up, the dns will point to
> 1.1.1.10 as my.server.com. when the 1.1.1.1 link goes down, i want the dns
> to point to 2.2.2.10 as my.server.com

ick. I don't like it, but the obvious solution is to have dns servers on
both netblocks handing out ip addresses for the same netblock that the DNS
server is on. That way you can have both feeds active at the same time,
you're much more likely to notice if something breaks instead of finding
out when you try to cutover to it because the main feed went down.
 
> I assume i could use some dynamic dns service, like dyndns.org, to update my
> dns record - they have 1 minute expiration time on dns records, or i could
> setup 2 dns servers serving my "server.com" zone, one will sit on 1.1.1.11
> and the other on 2.2.2.11. my isp will always try to replicate dns zones
> from the primay dns server 1.1.1.11, which will tell him that the address of
> my.server.com is 1.1.1.10, and if the isp is unable to get to 1.1.1.11 it
> will go to the secondary server, 2.2.2.11, and it will tell him that
> my.server.com address is 2.2.2.10
> 
> is there a better way to do that ?
> 
> Thanks.
> Alex.
> 
> 
> ------------------------------------------------------------------------------
> Linux HA Web Site:
>   http://linux-ha.org/
> Linux HA HOWTO:
>   http://metalab.unc.edu/pub/Linux/ALPHA/linux-ha/High-Availability-HOWTO.html
> ------------------------------------------------------------------------------
> 

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