[nycbug-talk] Re: [BSDCert] www.bsdcertification.org seems to be down

[alex at pilosoft.com]

On Thu, 26 May 2005, George Georgalis wrote:

> >It appears our provider experienced some outages yesterday. We're
> >working on creating more redundancy.
> >
> >Thanks for letting us know.
> 
> Well this brings to mind an idea of one of my clients. It sounds a bit
> kooky but I cannot think of a good reason not to do it, other than a
> little trickier to setup. You could call it a poor man's BGP.
> 
> Have two ISPs and subnets; make a common physical DMZ. Use a single
> server (or redundant as needed) with an ip alias for each subnet. For
> name resolution, use two resolvers, one on each subnet and have them
> serve the IPs of the subnet they are on.
<snip>
> 
> So... what's wrong with this setup? other than 2x the likelihood of an
> admin making a dns error. ;-)
Yes, that's been used by many products to do ghetto redundancy. 

The only thing that's wrong in this setup is fact that many DNS clients 
are broken and do not respect TTL. Windows 95/98 will cache DNS results 
forever. Certain web browsers are 'too smart' and will cache DNS results 
until browser is restarted. Certain ISPs (AOL did that, don't know if they 
do) enforce minimum 30 minutes TTL.

I.E. it will work in 99% of cases.

-alex