Jason--

Great question, and the simple answer would be "yes".
Unfortunately, the yes is also due for some conditions that need to be
satisfied.  

ISP side: customers are normally given at least 2 DNS server addresses
(IPs) just for what you mention, if one (primary) fails or needs to be
down for maintenance, etc, the other (and secondary or slave) would pick
up the slack when the lookup fails on the first. The TCP client on the
customer side should pick up on a failure almost immediately and try the
2nd listed server.

Hosting side: YUP, that's why NetSol and other registrars require 2 listed
DNS servers, in the event of a failure/line cut/maintenance on the first.  
Normally it's not a good idea to have 1 machine set up for
DNS/Mail/www/ftp/etc, since there is no failover.  A separate DNS server
(all it does is DNS) is the preferred method, and all is does is provide
name service.

The conditions are: needs to be configured properly and needs to be
accessable, listed, used, etc.  I'm guilty, I'm sure many people are,
2ndary DNS records are not my top priority in a day's work, but falling
behind snowballs very quickly.

The nice thing about bind, is that once the primary is configured
properly, and the 1st secondary has the right /etc/named.conf, additional
2ndary servers can be added by just copying the data from /etc/named.conf.
The records will be pulled upon a restart.  The TTL and SOA portions of
the DNS record can be tweaked for performance issues too.

You didn't specify whether you were coming from the ISP side (providing
DNS for dial/dsl/directconnect or hosting/website, so I addressed them
both.  There are details that effect both!

Any other ???s?

MK 


On Wed, 31 Jan 2001, Jason Sowers wrote:

> Those of you who use DNS/BIND all the time, question for you.  Does/can a
> "slave" server work as a redundant DNS server?  Is that technically the
> purpose.  If you guys could shed a little brief light on that subject it
> would be greatly appreciated.
> 
> Thanks
> 
> 
> ____________________________________
> Jason Sowers
> Network Engineer
> Open Systems International
> 3600 Holly Lane North Suite 40
> Minneapolis, MN 55447-1286
> Phone:  (763) 551-0559
> Fax:      (763) 551-1750
> Email: jsowers at osii.com <mailto:jsowers at osii.com>
> http:  www.osii.com <http://www.osii.com>  & www.e-scada.com
> <http://www.e-scada.com>
> 
> 
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> 

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