Re: [gentoo-user] Best caching dns server?

[Nilesh Govindrajan]

On Mon, May 21, 2012 at 1:17 AM, Alan McKinnon <alan.mckinnon@×××××.com> wrote:
>> Slow connection. See my previous reply to the list. I'm using pdnsd,
>> which can persist records and has every damn feature I wanted.
>>
>
> Fair enough, but consider this:
>
> If your connection is slow, the only thing you speeded up is the DNS
> lookups. Thereafter, everything else is still as slow as it ever was.
> And if you feel the need to speed up DNS lookups then the odds are very
> good that "everything else" is too slow i.e. not exactly usable.
>
> We get this a lot from our customers too, and the advise we give them
> is to look closely at their traffic throttling. In almost every case
> all UDP traffic has had the living crap throttled out of it somewhere
> by folk that don't really think things through, severely affecting
> dns and ntp as well as AV streaming.
>
> Throttled DNS rapidly gets out of hand, IIRC the last time we did some
> measurements it only takes around 5% of dns lookups to go wonky for the
> situation to rapidly spiral out of control - when dns fails the cache
> will try a TCP lookup and that's like wading through molasses.
>
> Our advice to customers is to first unthrottle dns and ntp completely,
> give it the highest possible priority (these are extremely light
> protocols and seldom show up on the radar when you do this), and see
> how that goes.
>
> It just seems to me that you *might* be trying a very unusual solution
> for a problem that is better handled one layer lower down.
>

Strictly speaking, my connection isn't too slow. I have a transfer
rate of 64 K/s (might sound ridiculous to you, but this costs 18$/mo
here).
OpenDNS lookups from my connection take something like 300 msec+ and
Google DNS lookups around 50 msec.

I can obviously use Google DNS, but as I said earlier, OpenDNS gives
me phishing protection and other that sort of stuff.

And hence I must use a local cache.

-- 
Nilesh Govindarajan
http://nileshgr.com