Help in learning Dig

[Kevin Darcy]

Dasari, Rao wrote:

> Can anyone point me to a good resource on the net in learning about how to
> use DIG and understand its output ?  Thanks in advance.

Well, if I post some tips here, then they'll be "on the net", right? Is that
good enough? :-)

If you're just starting out, you may want to go with a "simplified" format,
e.g. dig +pfmin +head {name}. The important parts of this output format are
the contents of the "status:" field (NOERROR, NXDOMAIN, SERVFAIL or
whatever), the contents of the "flags" field ("aa" means an authoritative
answer, "ra" means that the nameserver honors recursion) and the
"ANSWER SECTION" contents, which should appear at the end, if any. This
should suffice for normal lookups, although if you get a referral response
(non-authoritative NOERROR with an empty Answer section), you may have to
revert to a more verbose output format to see the referral information in the
Authority section of the response (or just add "+auth" to the command line to
see the Authority section contents).

As you learn more about DNS (get the _DNS_and_BIND_ O'Reilly book for general
information), you'll probably want to graduate to the default output format,
which also shows the contents of the Authority and Additional sections as
well as some statistical information (query round-trip time, server used,
timestamp and sent/received byte counts) at the end of the output.

Beyond default output format, there is a "+debug" option, but frankly
I haven't found it to be that useful in troubleshooting DNS problems.


- Kevin