glue record

[Stephane Bortzmeyer]

On Wed, May 13, 2009 at 11:46:29AM +0800,
 Tech W. <techwww at yahoo.com.cn> wrote 
 a message of 14 lines which said:

> When an upper DNS returns a domain's authorised DNS server, will it
> also returns the authorised DNS server's IP address? So glue record
> works as this way?

Why don't you test? Computer science is an experimental science.

% dig @a.nic.fr A www.google.fr

; <<>> DiG 9.5.1-P1 <<>> @a.nic.fr A www.google.fr
; (2 servers found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 47237
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.google.fr.                 IN      A

;; AUTHORITY SECTION:
google.fr.              172800  IN      NS      ns1.google.com.
google.fr.              172800  IN      NS      ns2.google.com.
google.fr.              172800  IN      NS      ns3.google.com.
google.fr.              172800  IN      NS      ns4.google.com.

;; Query time: 2 msec
;; SERVER: 192.93.0.129#53(192.93.0.129)
;; WHEN: Wed May 13 09:00:19 2009
;; MSG SIZE  rcvd: 124

No glue was sent back, since all google.fr nameservers are outside of
google.fr.


% dig @a.nic.fr A www.wanadoo.fr

; <<>> DiG 9.5.1-P1 <<>> @a.nic.fr A www.wanadoo.fr
; (2 servers found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29937
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 5
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.wanadoo.fr.                        IN      A

;; AUTHORITY SECTION:
wanadoo.fr.             172800  IN      NS      ns11.wanadoo.fr.
wanadoo.fr.             172800  IN      NS      ns.wanadoo.fr.
wanadoo.fr.             172800  IN      NS      ns2.wanadoo.fr.
wanadoo.fr.             172800  IN      NS      ns10.wanadoo.fr.

;; ADDITIONAL SECTION:
ns.wanadoo.fr.          172800  IN      A       80.12.255.24
ns2.wanadoo.fr.         172800  IN      A       80.12.255.159
ns10.wanadoo.fr.        172800  IN      A       80.12.255.23
ns11.wanadoo.fr.        172800  IN      A       80.12.255.152

;; Query time: 2 msec
;; SERVER: 192.93.0.129#53(192.93.0.129)
;; WHEN: Wed May 13 09:01:49 2009
;; MSG SIZE  rcvd: 180

Glue was sent back since wanadoo.fr's name servers are under
wanadoo.fr (so you could not find their IP addresses, without the glue
records).