Re: [DNSOP] "Optimization" in draft-ietf-dnsop-qname-minimisation

[Stephane Bortzmeyer <[e-mail]>]

On Tue, Jan 06, 2015 at 07:19:31AM -0800,
 Paul Vixie <[e-mail]> wrote 
 a message of 137 lines which said:

> that's true in an empty cache. but that emptiness will be short lived.
> at stead state, query-minimization has no more queries than
> longest-match.

And this point is already mentioned in the draft. Section 3 of -00:

   Qname minimisation can decrease performance in some cases, for
   instance for a deep domain name (like
   www.host.group.department.example.com where
   host.group.department.example.com is hosted on example.com's name
   servers).  For such a name, a cold resolver will, depending how qname
   minimisation is implemented, send more queries.  Once warm, there
   will be no difference with a traditional resolver.  A possible
   solution is to always use the traditional algorithm when the cache is
   cold and then to move to qname minimisation.  This will decrease the
   privacy a bit but will guarantee no degradation of performance.

> the qtype on those doesn't matter. they should probably use the
> original qtype,

There is a (very) small gain in privacy by using a "neutral" qtype
such as A or NS, especially for rare qtypes likes LOC or SRV.