[dns-operations] resolvers considered harmful

Stephane Bortzmeyer bortzmeyer at nic.fr
Thu Oct 23 16:34:48 UTC 2014

On Wed, Oct 22, 2014 at 11:03:11PM -0400,
 Mark Allman <mallman at icir.org> wrote 
 a message of 110 lines which said:

> The paper quantifies this cost for .com.  We find that something
> like 1% of the records change each week.  So, while increasing the
> TTL from the current two days to one week certainly sacrifices some
> possible flexibility, in practical terms the flexibility isn't being
> used.

There is no relationship between the data and the conclusion. Having a
short TTL is not because you make changes often, it's because, when
you decide to make a change, you want it to be effective rapidly. The
actual number of changes does not matter, what matter are the
expectations of users ("sorry, buddy, we made the change immediately
but it will not be seen by all caches before one week").

>     So, do we believe that it is incumbent upon (say) AT&T to
>     provide shared resolvers to shield (say) Google from a portion
>     of the DNS load?

Until now, it has been widely assumed (at least in Europe and America:
it's quite different in Asia and even more in Africa) that running a
proper and fast DNS resolver was one of the jobs of the Internet
access provider. We may decide differently (and the access providers
will rejoice) but, speaking as an end user, I do not see why I would
like AT&T to pay less and Google pay more (or the opposite).

Full disclosure: I'm not only an end user, I work for a TLD.

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