[dns-operations] behaviour of nameserver glue recs and TTL in referrals

[Mark E. Jeftovic]

Is the ADDITIONAL section the functional equivalent of the ANSWER
section in TLD roots now that most of them give out referrals when
queried for glue? Or would it only be used if the resolver can't
otherwise find the glue?

Where does the TTL come from in the ADDITIONAL section and can it be
modified by the superdomain operator of the nameserver?

In other words:

Marks-MacBook-Pro:~ markjeftovic1$ dig +norec ns6.zoneedit.co.uk @ns1.nic.uk

; <<>> DiG 9.8.5-P1 <<>> +norec ns6.zoneedit.co.uk @ns1.nic.uk
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35872
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 1

;; QUESTION SECTION:
;ns6.zoneedit.co.uk.		IN	A

;; AUTHORITY SECTION:
zoneedit.co.uk.		172800	IN	NS	ns6.zoneedit.co.uk.
zoneedit.co.uk.		172800	IN	NS	ns1.zoneedit.com.
zoneedit.co.uk.		172800	IN	NS	ns3.zoneedit.com.
zoneedit.co.uk.		172800	IN	NS	ns2.zoneedit.com.

;; ADDITIONAL SECTION:
ns6.zoneedit.co.uk.	172800	IN	A	166.88.18.59

;; Query time: 177 msec
;; SERVER: 195.66.240.130#53(195.66.240.130)
;; WHEN: Sat Feb 14 11:49:10 EST 2015
;; MSG SIZE  rcvd: 132

Where are the TTLs in the AUTHORITY and ADDITIONAL sections coming from
and can they be modified?

What factors would influence whether a resolver on a fresh query uses
the TTL from the referral vs the one from the authoritative NS for the
nameserver record itself?

Thanks.

- mark

-- 
Mark E. Jeftovic <markjr at easydns.com>
Founder & CEO, easyDNS Technologies Inc.
+1-(416)-535-8672 ext 225
Read my blog: http://markable.com