[NTLUG:Discuss] "Back up dns server"?

[Carl Haddick]

On Wed, Dec 05, 2007 at 05:26:54AM +0000, Leroy Tennison wrote:
> m m wrote:
> > 
> > 
> > 
> "DNS round-robin"
> 

Hostname lookups do not use DNS hostnames to find the DNS servers.
dns1.mydomain.com can be used as an authoritative DNS server for
mydomain.com.  If a client had to find dns1.mydomain.com to ask for
info on anything.mydomain.com, then you would have an unworkable
situation - you would never be able to find dns1.mydomain.com or
anything.mydomain.com.

The round robin is part of DNS servers I'm familiar with, and probably
with clients, as well.

Do a 'dig yahoo.com ns' several times.  The answer section will show the
hostnames of their authoritative name servers, ns1-ns8.yahoo.com, and
the additional section will show the IP addresses for those hostnames.
Each time you run dig with that command line, the name servers will be
listed in a different order.

Because of TTL as mentioned in another post and other reasons, failover
in DNS is just not a good solution.  

Good luck with that firewall problem,

Carl