512 byte limit

[Chris Thompson]

On Jan 22 2009, Stephane Bortzmeyer wrote:

[...]
>As mentioned by Anton Korotin, the root name servers send answers > 512.

Well not unless the EDNS flag and buffer size are set in the query, 
of course.

This prompted me to look at what data is omitted from the additional
section of the response for NS records for the root, when they are
limited to 512 bytes. 

 a, c, e, i & j.root-servers.net leave out both A and AAAA records
   for k, l & m, putting in all records for the others.
 b, d, f, g, h, k, l & m.root-servers.net include all the A records,
   and leave out enough AAAA records to make the answer fit.

Both entirely legal, of course.

-- 
Chris Thompson
Email: cet1 at cam.ac.uk