Re: [PLUG] Alternate Server IP address

[gabriel rosenkoetter <gr@eclipsed.net>]

[David, it'd be nice if you could wrap your text at a reasonably
column--say, about 70--so that it displays within the window for
those of us on standard 80 column terminals. It'd be easier to read
and reply to if you did.]

On Thu, Jul 11, 2002 at 10:05:27AM -0400, David Hull wrote:
>     I was wondering if any of you might know if it is possible
> to have an alternate IP address for a web server.
> I.E.  if my primary server is unavailable, someone trying to
> reach my webpage will be redirected to an alternate
> server.  Thanks in advance.

Provided you control the DNS, you can do this fairly easily,
conceptually. (The details are a bit complicated, but if you
understand BIND it should be no big deal.) Basically, just monitor a
heartbeat from the main server at the DNS machine and, if the web
server should fall off the network, change your A record (don't
forget to change the serial number too) and push out an update to
anything mirroring from your DNS. Keeping the TTL fairly low on that
zone (say, a couple of hours) will ensure minimal downtime even for
those who have the DNS information cached.

Using BIND 9 and D(ynamic)DNS would be even better (and easier to
configure), as the DNS would just issue a DDNS update when it
stopped seeing the webserver, switching the hostname to the failover
IP address, and issue another DDNS update when the host reappeared.

-- 
gabriel rosenkoetter
gr@eclipsed.net

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