OT - Small DNS "appliances" for remote offices.

Thu Feb 19 02:37:37 UTC 2015

On Wed, Feb 18, 2015 at 10:22 AM, Rob Seastrom <rs at seastrom.com> wrote:
> The Pi is low-powered in more ways than one.  Last fall I ran some
> (admittedly fairly simple minded) DNS benchmarks against a Raspberry
> Pi Model B and an ODROID U3.
>
> Particularly if you have DNSSEC validation enabled, the Pi is
> underwhelming in performance (81 qps in the validation case, 164
> without).
>
> The U3 is circa 325 qps with or without DNSSEC validation on, which
> suggests that something else other than crypto-computes is the long
> pole in the tent.

Hi Rob,

Interesting. The odroid has a 1700 mhz processor, the pi a 700 mhz
processor. Except for the validation anomaly your results are
self-consistent.

> Caveats: This is just returning NXDOMAIN against a TLD for which
> (after the first run) there is already cached information that the TLD
> is bogus, so this test doesn't involve traffic actually leaving the box.

Given your testing methodology, the difference between validating and
non-validating makes no sense to me. Once the records are cached bind
should only be passing a flag around? Weird.

On Wed, Feb 18, 2015 at 6:44 PM, Peter Loron <peterl at standingwave.org> wrote:
> For any site where you would use a Pi as the DNS cache, it won't be an
> issue. DNS isn't that heavy at those query rates.

Yes and no. DNS is a lynchpin service. All connections stall until the
DNS provides an IP address. So you kinda want low latency in your DNS
lookups. If a fast server three hops away can respond faster than a
slow server on the same LAN, the server three hops away is a better
choice.

A point in favor of the Raspberry Pi -- there's a heckuva lot of
accessories already built for it. Including various cases and even a
few different rackmount cases. And a wealth of "how do you do it?" and
"why did it do this?" information available with just a few google
search terms. The communities supporting the other hardware options
are not nearly so large.

Regards,
Bill Herrin

-- 
William Herrin ................ herrin at dirtside.com  bill at herrin.us
Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/>