ns delegation, unix dig vs dnsjava dig vs dnsjava Lookup

[Stefano B. <sou...@ba...>]

Hi all,

my limited dns knowledge don't let me to reach a conclusion about this
issue.


If I ask MX servers for that domain to that server, no MX found.
--------------------
# host -t mx zunft-oberstrass.ch. 194.246.118.118
Using domain server:
Name: 194.246.118.118
Address: 194.246.118.118#53
Aliases:

zunft-oberstrass.ch has no MX record
----------------

if I ask any type I get 2 NS records
----------------
# host -a zunft-oberstrass.ch. 194.246.118.118
Trying "zunft-oberstrass.ch"
Using domain server:
Name: 194.246.118.118
Address: 194.246.118.118#53
Aliases:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61311
;; flags: qr rd; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 0

;; QUESTION SECTION:
;zunft-oberstrass.ch.           IN      ANY

;; ANSWER SECTION:
zunft-oberstrass.ch.    49631   IN      NS      ns2.nameserver.ch.
zunft-oberstrass.ch.    49631   IN      NS      ns1.nameserver.ch.

;; AUTHORITY SECTION:
zunft-oberstrass.ch.    49631   IN      NS      ns2.nameserver.ch.
zunft-oberstrass.ch.    49631   IN      NS      ns1.nameserver.ch.

Received 112 bytes from 194.246.118.118#53 in 11 ms
--------------------

If I ask the MX to one of the delegated NS I found an answer.
--------------------
# host -t mx zunft-oberstrass.ch. ns2.nameserver.ch.
Using domain server:
Name: ns2.nameserver.ch.
Address: 217.71.81.4#53
Aliases:

zunft-oberstrass.ch mail is handled by 10 mail.zunft-oberstrass.ch.
--------------------


Now, the same thing using unix dig:
----------------------
# dig @194.246.118.118 zunft-oberstrass.ch. mx

; <<>> DiG 9.3.2 <<>> @194.246.118.118 zunft-oberstrass.ch. mx
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 52236
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 0

;; QUESTION SECTION:
;zunft-oberstrass.ch.           IN      MX

;; AUTHORITY SECTION:
zunft-oberstrass.ch.    49470   IN      NS      ns2.nameserver.ch.
zunft-oberstrass.ch.    49470   IN      NS      ns1.nameserver.ch.

;; Query time: 10 msec
;; SERVER: 194.246.118.118#53(194.246.118.118)
;; WHEN: Tue Jul 17 11:03:38 2007
;; MSG SIZE  rcvd: 84
--------------------------
So, no MX record found, but it returns the 2 NS like "host" did.


Now dnsjava dig command line:
--------------------
#java -cp dnsjava-2.0.3.jar dig @194.246.118.118 zunft-oberstrass.ch. mx
; java dig 0.0
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31604
;; flags: qr rd ra ; qd: 1 an: 1 au: 2 ad: 2
;; QUESTIONS:
;;      zunft-oberstrass.ch., type = MX, class = IN

;; ANSWERS:
zunft-oberstrass.ch.    3516    IN      MX      10 mail.zunft-oberstrass.ch.

;; AUTHORITY RECORDS:
zunft-oberstrass.ch.    86316   IN      NS      ns1.nameserver.ch.
zunft-oberstrass.ch.    86316   IN      NS      ns2.nameserver.ch.

;; ADDITIONAL RECORDS:
mail.zunft-oberstrass.ch.       3516    IN      A       195.129.94.130
mail.zunft-oberstrass.ch.       3516    IN      A       195.129.94.194

;; Message size: 137 bytes
;; Query time: 138 ms
--------------------
It finds the MX record!!


Can anyone explain me why there is such a difference and if this is a
result of a buggy server or where is the problem?

Is this only a difference between "recursive" client (dnsjava dig) and
"non recursive" client (unix dig)?

Thank you,
Stefano