DNS trace tools

[AY Xu]

I have a RHEL 3 box. Because of DNS query problem, we can't send mail
to domain carrier.utc.com. Our email server locate in Shanghai/China,
carrier.utc.com was in USA. I use bellow command to query:
[root at mail root]# dig -t mx carrier.utc.com
; <<>> DiG 9.2.2 <<>> -t mx carrier.utc.com
;; global options:  printcmd
;; connection timed out; no servers could be reached
[root at mail root]# dig @202.96.209.5 -t mx carrier.utc.com

; <<>> DiG 9.2.2 <<>> @202.96.209.5 -t mx carrier.utc.com
;; global options:  printcmd
;; connection timed out; no servers could be reached
----------------------------------------------------------
202.96.209.5 was the DNS server from our ISP.
But sometime we can query MX record successfully. We can query other
domains without any problem.

My question is: Is there any tools we can use to trace what's could be
the problem. In short, I'm looking for a DNS debug tool.

Any suggestions?
Thank you

xu zuoyin
05/07/08