DIG - Connection Timeout for one ISP

Hi everyone

Ive seen various postings on this, but cant seem to find anything possibly
related to my problem.

Im running a Linux BOx (Redhat) as a NameServer running BIND (9.2.1-16). It
hosts the DNS and Mail for various virtual domains I host. All has (it
appears atleast :-) ) been running OK for a few years now ... and from most
accounts still is. Ive got one site which has problems with "one ISP" being
unable to reliably connect 100% of the time. It appears to be a name
resolution problem (eg traceroute via IP and name suggest this).

My Linux box is running IPChains, but is open for port 53 (TCP/UDP)

When I do a DIG @ the ISP's name server, I get regular timeouts. When I use
their stated secondary, timeouts never occur. EG.

[craig@ns1 craig]$ dig @ns1.argonaut.com.au investorIQ.com.au
; <<>> DiG 9.2.1 <<>> @ns1.argonaut.com.au investorIQ.com.au
;; global options: printcmd
;; connection timed out; no servers could be reached

whilst

[root@ns1 virtual]# dig @ns1.webace.com.au ANY investorIQ.com.au

; <<>> DiG 9.2.1 <<>> @ns1.webace.com.au ANY investorIQ.com.au
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61513
;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 2, ADDITIONAL: 3

;; QUESTION SECTION:
;investorIQ.com.au. IN ANY

;; ANSWER SECTION:
investorIQ.com.au. 34223 IN MX 10 ns1.infobahn.co.nz.
investorIQ.com.au. 34223 IN MX 5 mail.investorIQ.com.au.
investorIQ.com.au. 34223 IN A 219.88.230.9
investorIQ.com.au. 34223 IN NS ns1.infobahn.co.nz.
investorIQ.com.au. 34223 IN NS ns2.infobahn.co.nz.
investorIQ.com.au. 34223 IN SOA ns1.infobahn.co.nz.
hostmaster.infobahn.co.nz. 2004040416 14400 3600 604800 86400

;; AUTHORITY SECTION:
investorIQ.com.au. 34223 IN NS ns1.infobahn.co.nz.
investorIQ.com.au. 34223 IN NS ns2.infobahn.co.nz.

;; ADDITIONAL SECTION:
ns1.infobahn.co.nz. 5450 IN A 219.88.230.7
mail.investorIQ.com.au. 34223 IN A 203.59.8.105
ns2.infobahn.co.nz. 5456 IN A 219.88.230.8

;; Query time: 88 msec
;; SERVER: 203.17.62.246#53(ns1.webace.com.au)
;; WHEN: Wed Jun 9 09:48:38 2004
;; MSG SIZE rcvd: 261


From a quick check at http://www.dnstools.com and
http://www.squish.net/dnscheck/ shows some potential problems with
au2ld.CSIRO.au, but other than that most seems OK?

After a short wait, a second DIG will give:

[craig@ns1 craig]$ dig @ns1.argonaut.com.au ANY investorIQ.com.au
; <<>> DiG 9.2.1 <<>> @ns1.argonaut.com.au ANY investorIQ.com.au
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57157
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 0

;; QUESTION SECTION:
;investorIQ.com.au. IN ANY

;; ANSWER SECTION:
investorIQ.com.au. 3420 IN NS ns2.infobahn.co.nz.
investorIQ.com.au. 3420 IN NS ns1.infobahn.co.nz.

;; AUTHORITY SECTION:
investorIQ.com.au. 3420 IN NS ns2.infobahn.co.nz.
investorIQ.com.au. 3420 IN NS ns1.infobahn.co.nz.

;; Query time: 133 msec
;; SERVER: 203.17.62.245#53(ns1.argonaut.com.au)
;; WHEN: Wed Jun 9 09:33:50 2004
;; MSG SIZE rcvd: 130

or

[craig@ns1 craig]$ dig @ns1.argonaut.com.au ANY investorIQ.com.au
; <<>> DiG 9.2.1 <<>> @ns1.argonaut.com.au ANY investorIQ.com.au
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17084
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;investorIQ.com.au. IN ANY

;; ANSWER SECTION:
investorIQ.com.au. 3399 IN NS ns1.infobahn.co.nz.
investorIQ.com.au. 3399 IN NS ns2.infobahn.co.nz.
investorIQ.com.au. 86383 IN A 219.88.230.9

;; AUTHORITY SECTION:
investorIQ.com.au. 3399 IN NS ns1.infobahn.co.nz.
investorIQ.com.au. 3399 IN NS ns2.infobahn.co.nz.

;; ADDITIONAL SECTION:
ns1.infobahn.co.nz. 86378 IN A 219.88.230.7
ns2.infobahn.co.nz. 86378 IN A 219.88.230.8

;; Query time: 86 msec
;; SERVER: 203.17.62.245#53(ns1.argonaut.com.au)
;; WHEN: Wed Jun 9 09:57:07 2004
;; MSG SIZE rcvd: 161

a) Any ideas why a person using ns1.argonaut.com.au gets periodic lookup
failures?
b) Why that name server speciftically sometimes timesout?
c) Why a DIG ANY gives two different outputs for the same name server
(ns1.argonaut.com.au)
d) Have I stuffed anything big time in my own setup?

Any help would be greatly appreciated.

Cheers

Craig