[geeks] Remote Failover

[Lionel Peterson]

>From: Sridhar Ayengar <ploopster at gmail.com>
>Date: 2008/05/20 Tue AM 11:47:43 EDT
>To: The Geeks List <geeks at sunhelp.org>
>Subject: [geeks] Remote Failover

>Anyone have a pointer to where I might find some information about 
>configuring a pair of Apache servers and a DNS infrastructure to perform 
>remote web server failover?
>
>I'd like it to happen something like:
>
>1.	One of the web servers notices that another is down.
>
>2.	The web server that noticed the error sends a message to the DNS 
>server updating the "www" CNAME to remove the downed machine.
>
>3.	The downed machine comes back up and notices that it is no longer in 
>the DNS round-robin so it sends a message to the DNS server to add 
>itself back into the "www" CNAME.
>
>Of course, I could write code (or even shell scripts) to do all of this, 
>but I'd rather not reinvent the wheel if there is a solution already 
>available.

I'm asking because I don't know:

You set up two servers, one at 10.0.0.1 and another at 10.0.0.2[0], and point a public DNS record at 10.0.0.1.

I browse your web site, and I get a record for 10.0.0.1 and I cache that locally.

Then your first web server goes down, and you update public DNS to point to 10.0.0.2.

If I return to your site and my cached DNS record has not expired, will my browser find your new IP address for your server? Will it only become available once my cached DNS records expire and I query the public DNS servers and retrieve your new IP address for the second server?

Again, I ask because I don't know, and I'm not sure how to find the answer without reading a *ton* of material...

Thanks,

Lionel