[bind10-dev] Suboptimal way of splitting XFR-out to messages

[Peter Koch]

On Tue, Dec 06, 2011 at 10:29:04AM +1100, Mark Andrews wrote:

> Additionally using messages sizes large than 16K by itself lead to
> sub-optimal compression as only the first 16K is available as targets
> of compression pointers.  If you want to have optimal compression
> you need to start a new message whenever the message overhead is
> less than what is lost due to not having a compression target

true, but given that with new (and upcoming) RR types, the only available
compression target will be the owner name (as per RFC3596(bis)), and
(bravely) assuming that most zones have kind of a flat internal
structure(*), not sure what this optimal compression is going to achieve.

However, the difference might be bigger for large delegation centric
zones with (as of today) short $ORIGINS, paired NS RRs and NS RR 'DNAME'
available as a compression target.  Then again, if the XFR travels
along an encrypted channel, the final gain achieved by DNS level
compression might be even less significant.

-Peter

(*) The underscore endeavour might render this very assumption void.