Problems resolving a domain (oum.edu.my)

[Elias]

Dear experts,
I'm running BIND 8.3.4 on a Solaris machine as a caching + authoritative server. I've got no problems resolving domains except for this particular one. My problem is that this domain is very intermittent. Sometimes it will be OK for 2-3 days while sometimes it will only be OK for less than 30 minutes. I've run several traces to see if this is a problem with my firewall or setup, but I can't seem to find anything wrong with it. I've also tried bypassing my firewall completely but the problem is still there. When the domain does not resolve, I just need to do a 'ndc reload' and immediately the domain will be OK again. As you can see from the trace log below, the authoritative servers for oum.edu.my doesn't seem to be answering to my queries, but after a reload (the 30th packet), everything goes back to normal. My machine is equipped with 512MB RAM and there is always around 50% free memory left. CPU is utilized like 60% at max.

# snoop -r port 53 | grep oum   
Using device /dev/hme (promiscuous mode)
1 192.168.1.53 -> 202.185.23.4 DNS C www.oum.edu.my. Internet Addr ?
2 192.168.1.53 -> 218.208.3.100 DNS C webmail.oum.edu.my. Internet Addr ?
3 192.168.1.53 -> 218.208.3.100 DNS C webmail.oum.edu.my. Internet Addr ?
4 192.168.1.53 -> 202.185.23.4 DNS C webmail.oum.edu.my. Internet Addr ?
5 192.168.1.53 -> 218.208.3.100 DNS C webmail.oum.edu.my. Internet Addr ?
6 192.168.1.53 -> 202.185.23.4 DNS C www.oum.edu.my. Internet Addr ?
7 192.168.1.53 -> 218.208.3.100 DNS C oum.edu.my. Internet Addr ?
8 192.168.1.53 -> 202.185.23.4 DNS C oum.edu.my. Internet Addr ?
9 192.168.1.53 -> 202.185.23.4 DNS C webmail.oum.edu.my. Internet Addr ?
10 192.168.1.53 -> 202.185.23.4 DNS C webmail.oum.edu.my. Internet Addr ?
11 192.168.1.53 -> 218.208.3.100 DNS C oum.edu.my. Internet Addr ?
12 192.168.1.53 -> 218.208.3.100 DNS C webmail.oum.edu.my. Internet Addr ?
13 192.168.1.53 -> 218.208.3.100 DNS C iportal.oum.edu.my. Internet Addr ?
14 192.168.1.53 -> 202.185.23.4 DNS C oum.edu.my. Internet Addr ?
15 192.168.1.53 -> 218.208.3.100 DNS C icampus.oum.edu.my. Internet Addr ?
16 192.168.1.53 -> 202.185.23.4 DNS C iportal.oum.edu.my. Internet Addr ?
17 192.168.1.53 -> 202.185.23.4 DNS C icampus.oum.edu.my. Internet Addr ?
18 192.168.1.53 -> 218.208.3.100 DNS C iportal.oum.edu.my. Internet Addr ?
19 192.168.1.53 -> 218.208.3.100 DNS C oum.edu.my. Internet Addr ?
20 192.168.1.53 -> 218.208.3.100 DNS C icampus.oum.edu.my. Internet Addr ?
21 192.168.1.53 -> 218.208.3.100 DNS C www.oum.edu.my. Internet Addr ?
22 192.168.1.53 -> 202.185.23.4 DNS C webmail.oum.edu.my. Internet Addr ?
23 192.168.1.53 -> 202.185.23.4 DNS C iportal.oum.edu.my. Internet Addr ?
24 192.168.1.53 -> 202.185.23.4 DNS C www.oum.edu.my. Internet Addr ?
25 192.168.1.53 -> 202.185.23.4 DNS C icampus.oum.edu.my. Internet Addr ?
26 192.168.1.53 -> 218.208.3.100 DNS C www.oum.edu.my. Internet Addr ?
27 192.168.1.53 -> 218.208.3.100 DNS C iportal.oum.edu.my. Internet Addr ?
28 192.168.1.53 -> 202.185.23.4 DNS C oum.edu.my. Internet Addr ?
29 192.168.1.53 -> 218.208.3.100 DNS C icampus.oum.edu.my. Internet Addr ?
30 192.168.1.53 -> 218.208.3.100 DNS C www.oum.edu.my. Internet Addr ?
31 218.208.3.100 -> 192.168.1.53 DNS R www.oum.edu.my. Internet Addr 218.208.3.108
32 192.168.1.53 -> 218.208.3.100 DNS C webmail.oum.edu.my. Internet Addr ?
33 218.208.3.100 -> 192.168.1.53 DNS R webmail.oum.edu.my. Internet Addr 202.185.23.15
34 192.168.1.53 -> 218.208.3.100 DNS C icampus.oum.edu.my. Internet Addr ?
35 218.208.3.100 -> 192.168.1.53 DNS R icampus.oum.edu.my. Internet Addr 202.185.23.21


Thank you

- Elias -