[dns-operations] Limit on Name Servers & their IPs for a sub-domain

[Stephane Bortzmeyer]

On Thu, Jan 11, 2018 at 03:11:00PM +0000,
 James Stevens <James.Stevens at jrcs.co.uk> wrote 
 a message of 26 lines which said:

> I am aware of the "traditional" limit of 13 NS records for a sub-domain, is
> it considered that this still applies?

I don't think that it ever applied (it depends on the names, because
of compression). Today, with EDNS, it is even more "historical
interest only". The Yeti root has 25 name servers at the apex :-)

To bad this draft was never published but it is a good reading
<https://datatracker.ietf.org/doc/draft-ietf-dnsop-respsize/>

> But, I only tested a small number of address - is there some reason
> (e.g.  packet size, code restrictions, etc) that might mean more
> addresses would not scale?

There is probably a limit in some/all resolvers for the number of IP
addresses they will try for a given zone.