I'm trying to design a way so if host "A" fails Host "B" will take over.
If my computer can not connect to Host "A" DNS will resolve to go to Host "B".
I was hoping in anyone could help me how to set this up using a DNS server.
thanks

that's automatic in the TCP config. If you look, there should be TWO DNS addresses.
Failure on the first (or a timeout) will cause the second to be used.

HOWEVER: you can't just slam in any two DNS addresses!

If you want to use manual DNS configuration, then you must be able to use

run->cmd
nslookup www.google.com dns-addr-1
nslookup www.google.com dns-addr-2

both requestions must return an IP address for google -- anything else will mean
that the dns-addr-x used may be valid but is not configured for a recursive query and
you MUST find some other dns address to use.

You would be better off using the TCP DHCP supplied DNS address(es)

Have you considered OpenDNS.com? Check it out.

The file /etc/resolv.conf is where your current DNS settings are stored.

What exactly is your concern with DNS? Are you having trouble with your ISP's DNS servers not responding?

I strongly suggest NOT using OpenDNS.

Can you qualify that recommendation please. There are several good reasons for
using it, including avoiding the DNS poisoning threat.

see Computerworld article