Can one mirror a web server ?

[Jim Popovitch]

On Wed, 2005-02-02 at 15:53 -0500, barrett bonden wrote:
> Can one mirror a web server ?
> 
> The idea is to make a  failsafe  and transparent dual computer system at two
> sites.
> 
> This would involve (can it be done ?) one dns setting point to two ip
> addresses ?

Yes/No.

Yes: It can be done such that www.yourdomain.com resolves to multiple IP
addresses.  Do a `host www.google.com` for an example.

No: What you will get with multiple A records is... well... multiple A
records.  One user will get the first, the next visitor will get the
second, the third visitor will get the third.  This achieves
load-distribution, but not failover.  In the event that one IP goes
dead, that A record will still be distributed and the "lucky" visitor
will get a page timeout.

Question for Bind developers:  Wny couldn't a feature (defaulted to off)
be added that allows for a simple ICMP test before a request is
returned. Yes it would slow things down, but it could allow for
rudimentary failover.  Just a thought.

-Jim P.