Caching DNS for dialup

[Peter Risdon]

Jonathon McKitrick wrote:
> On Wed, Nov 24, 2004 at 05:07:20PM +0000, Peter Risdon wrote:
> : A caching DNS server would help conserve bandwidth on a dialup 
> : connection - I generally run one myself with any connection with limited 
> : bandwidth.
> 
> After RTFM, I believe I have it up and running.  ;-)
> 
> Named is running, but how can I be sure the caching is working?

I'm rusty with bind - I've been using djbdns for the last few years. But 
the way to find out whether it's *working* is to query it directly:

dig @your.gateway.server.ip.or.hostname www.google.com

On the machine itself, dig at localhost ... should be fine.

or whatever. If it's working, you'll get a load of stuff back, including 
a line like this:

;; flags: qr rd aa ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

Do the query again and it should look like this[1]:

;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

ie. no *aa*. If that's what you get, it's caching. The *aa* means *I 
went out on the network for this answer*


> 
> Also, does it make sense to do this on each box, or just the gateway?

Just the gateway.

Peter.

[1] I looked this up because I don't use bind... With dnscache (the 
djbdns caching server, I tail the relevant log to see what it's doing, 
and look directly at the cache. I tried this with dnscache and it didn't 
work :-/ So I am assuming that bind handles these flags differently.

-- 

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