multiple A records for the same host

[Chris Buxton]

At 11:56 AM +0530 6/5/01, sanjay singh wrote:
>Hi
>
>If we have multiple A records  pointing to different IP (in DNS) for a
>particular domain like
>
>www A     192.168.0.1
>          A     192.168.0.2
>          A     192.168.0.3
>
>it will work in round robin.. right. My question is suppose one of the 3
>machines is not working then how it will replicate to next one?

It won't. Round-robin load sharing provides absolutely no fault tolerance.

If you want DNS-based fault tolerance and (with some solutions) the 
possibility of asymmetric load balancing, there are solutions out 
there. Bind by itself does not offer such.

Solutions of which I'm aware:

- There is some Perl-based system somewhere (I believe it's freeware) 
that works with Bind. I know no other details, including where to 
find it. Perhaps someone else on the list knows.

- There are dedicated DNS servers (little router-like boxes) that do 
a fine job of this. You'd delegate www as a subdomain to the box. 
Depending on your budget, the price of such things may be a problem.

- My company offers a solution, but it means forgoing Bind and a 
Unix-like OS altogether. We're not pushing it at the moment, because 
we don't offer it on most of the platforms we support. If you're 
willing to consider using Mac OS (9 or earlier, not X) for your DNS 
servers, let me know off-list and I'll fill you in.
____________________________________________________________________

Chris Buxton <cbuxton at menandmice.com>

Men & Mice <http://www.menandmice.com/> offers:
  - DNS training, including Active Directory
  - QuickDNS, a DNS management system for servers on Linux & Mac OS
    (Solaris support coming soon!)
  - DNS Expert, a DNS analysis and troubleshooting utility
____________________________________________________________________