From: werner@physics.uq.oz.au (Michael Werner)
Subject: Re: DNS/named: Caching vs. Forwarding Server?
Reply-To: werner@dirac.physics.uq.oz.au
Organization: Department of Physics, University of Queensland
Date: Sun, 13 Sep 1992 08:46:03 GMT

In article <rhoward.716215294@matd>, rhoward@matd.gatech.edu (Robert L. Howard) writes:
|> craig@ec.uwa.oz.au (Craig Richmond - division) writes:
|> 
|> >rhoward@matd.gatech.edu (Robert L. Howard) writes:
|> 
|> [questions about caching vs. forwarding name servers]
|> 
|> >>The problem is that I don't understand quite the subtle 
|> >>difference between the two.  What I desire is that when
|> >>the DS-1 link is down that I will at least have minimal
|> >>DNS for those hosts local to me, which would probably
|> >>be in the cache.  (Ideally, I'd also like some way to force
|> >>some list of hosts into the cache right at boot time so if
|> >>the DS-1 link goes down 3 minutes later, I will have more
|> >>than 2 hosts in the cache.)
|> 
|> >How about setting yourself up as a primary name server, but put your entry
|> >as the second name server in the resolv.conf file on all your machines.
|> >This way it won't go around putting things in the cache left right and
|> >centre.  Only if your normal name server fails a lookup.
|> 
|> But that still forces some large amount of lookups over the DS-1
|> link.  I would think that I *want* to have stuff in a (more) local
|> cache to save time.
|> 
|> >You could put the local machines into a cache file.  named can be set up
|> >with a cache file of DNS information to be cached at startup.
|> 
|> Okay, here is what I think I know about a cache file.  The examples
|> I have seen have a line in named.boot like:
|> 
|> cache	.	/etc/named.ca
|> 
|> which I understood to cause named to read in and cache the root
|> servers (the example had named.ca with the names of the top level
|> root servers in it).  Does this mean I can add another cache line
|> like:
|> 
|> cache	whatever.gatech.edu	/etc/named.local.ca
|> 
|> and put my hosts that I want always cached in it?
	I only set up my named.boot and root.cache files today so I
	know little so far but it may be enough to help out.
	You can have more than one cache file but I haven't tried it.
|> 
|> Still, what about the forwarding server issue?  Could I add cache
|> lines like above an also add a forwarders' line to the boot file
|> so that all (non-cached) requests would go directly to the campus
|> name server?  Do I even want to bother with this?

	If you are only using cache entries in your named.boot file
	then you can nominate nameservers within local.ca without
	any need for forwarders. e.g

	.	IN	NS	nameserver.(full machine name plus .)
nameserver.	IN	A	nameserver(full IP address) 
                                       
	From my ignorant standpoint, if you don't have any primary entries
	then use of a forwarders entry as opposed to the above example
	does not appear to be important.
-- 
Yours,

Mike

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+                                                                          +
+    *		  *			Michael Werner		           +
+     *		 *	    		werner@dirac.physics.uq.oz.au      +
+      * 	*			Theoretical Quantum Optics,        + 
+       -------		                Department of Physics,             +
+      *       *                        University of Queensland.          +
+     *		*			St. Lucia. 4072. Australia         +
+    *           *                                                         +
+                                                                          +   
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