How to know the reason of SERVFAIL

[Watanabe, Hiroshi (HP-Partner)]

I'm using BIND9.2.3 on True64 Unix as cache server.
When I query some domain, status SERVFAIL is returned.

How can I know the details of reasons for SERVFAIL.
For example,  "No NSs with CNAMEs",  "Lame nameservers" ... so on.

Is there any logging method for this?

Thanks,
Hiroshi