[dns-operations] All dual-stack DNS servers - any problem with it?

[Mark Andrews]

> Olivier Guillard / AFNIC p=ED=B9e v St 16. 05. 2007 v 15:30 +0200:
> > Hi Ondrej,
> > =
> 
> > Will the size of DNS responses to .cz queries
> > still fit in 512 octets ?
> 
> According to my calculations and test with bind9 and nsd it should and
> we should be able to add two more before we reach the limit.  If I am
> miscalculating something lemme know.
> 
> I used http://www.rfc1925.org/root.zone as base for my calculations.
> 
> --cut here--
> * Current state (A.NS - F.NS; E.NS is only IPv4) *
> ;; MSG SIZE  rcvd: 359
> 
> * Current state (A.NS - F.NS; full dual stack): *
> ;; MSG SIZE  rcvd: 387
> 
> * +1 NS (A.NS - G.NS; dual stack) *
> ;; MSG SIZE  rcvd: 447
> 
> * +2 NS (A.NS - H.NS; dual stack) *
> ;; MSG SIZE  rcvd: 507
> 
> --cut here--

	A minimal referral is 333 octets (below).

	A typical referral in 394 octets (63 character hostname).

	Each AAAA record takes 28 octets, and you need three
	to become all dual stacked.

		394 + 3 * 28 => 478
 
	The roots would start dropping glue for plain DNS queries
	once the name to be looked up exceeds 97 characters.

	For comparision a minimal referral to COM is 509 octets
	and glue records are dropped once the name to be looked up
	exceeds 7 characters. i.e. just about every referral from
	the root to the COM servers has incomplete glue.

	Mark

; <<>> DiG 9.3.4 <<>> ns cz @a.root-servers.net +norec
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28278
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 6, ADDITIONAL: 9

;; QUESTION SECTION:
;cz.				IN	NS

;; AUTHORITY SECTION:
cz.			172800	IN	NS	C.NS.NIC.cz.
cz.			172800	IN	NS	E.NS.NIC.cz.
cz.			172800	IN	NS	F.NS.CZNIC.EU.
cz.			172800	IN	NS	NS.TLD.cz.
cz.			172800	IN	NS	NSS.TLD.cz.
cz.			172800	IN	NS	NS-EXT.ISC.ORG.

;; ADDITIONAL SECTION:
C.NS.NIC.cz.		172800	IN	A	195.66.241.202
C.NS.NIC.cz.		172800	IN	AAAA	2a01:40:1000::2
E.NS.NIC.cz.		172800	IN	A	194.146.105.38
F.NS.CZNIC.EU.		172800	IN	A	193.171.255.48
F.NS.CZNIC.EU.		172800	IN	AAAA	2001:628:453:420::48
NS.TLD.cz.		172800	IN	A	217.31.196.10
NSS.TLD.cz.		172800	IN	A	217.31.200.10
NS-EXT.ISC.ORG.		172800	IN	A	204.152.184.64
NS-EXT.ISC.ORG.		172800	IN	AAAA	2001:4f8:0:2::13

;; Query time: 236 msec
;; SERVER: 198.41.0.4#53(198.41.0.4)
;; WHEN: Thu May 17 01:04:42 2007
;; MSG SIZE  rcvd: 333

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org