RE: [cobalt-users] Re: Simple Question...pointing .net to .com

[flash22@xxxxxxx]

On Tue, 19 Dec 2000, Rodolfo J. Paiz (E-mail) wrote:

> > Actually Rodolfo, A records may return, and MX records usually do
> 
>I set up DNS to return two IP addresses for each host, again one from
each
> provider. Wouldn't this mean that, even if one upstream dies, the client
> browser can use the other IP to get to me?
> 
> Too good to be true, right?

Yes...how does the browser know which IP works and which has failed?
What you are heading towards is round-robin dns, and in theory it can
provide a 'poor mans' redundency solution, but yo need a somewhat more
spohisticated method than this, you need to slave each server to the other
so that when the server dies it's IP address goes away as well,a nd you
need to run short expire times so that clients get new dns records without
the dead IP address in them, and even after you do all this it may still
not work well, as isp's cache beyong TTL's, clients are stupid etc...

The configuration you describe is however, fairly commn as a way of load
sharing, since requests are divided up between the 2 servers, assuming you
are willing to keep duplicate content , or are setting them up for
services where fallback is easy (eg mail relay/hosts)...

g