[c-nsp] Cache DNS servers

[sthaug at nethelp.no]

> > I have little question about DNS servers that you use in your environment?
> > We use bind on freebsd servers now. I did some benchmarks and found that
> > google public DNS is 8 - 10 time faster than my own. So I decide change BIND
> > for something more faster. I'm in MNO market.  Any suggestions?
> 
> 
> just caching resolver? might want to look at unbound.... but google 10x faster than you even though
> theirs are remote etc?  
> 
> 1) tune your server (MANY things can be done)
> 2) their caches are probably ready-populated with loads of stuff as they are operational..whereas your server
> will have to go out to make queries.

Ayup, this is mostly about "hot caches". You need a significant amount
of DNS query traffic to get a good cache that will answer most queries
quickly, out of the cache.

FreeBSD or Linux, BIND, Unbound or PowerDNS recursor - use what you
know best, they will all work well for normal loads. If you're getting
into more than 10k queries/second territory you may want to actually
do some testing/measurement.

Given a nice hot cache, a nearby resolver is likely to beat a remote
Google resolver, simply due to the lower latency to reach the cache.
Yes, I have measurements that show this :-) 

But simply replacing BIND with something else is *not* likely to solve
your problem.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no