"O Tiger-lily!" said Alice, addressing herself to one that was waving gracefully about in the wind, "I wish you could talk!"
"We can talk," said the Tiger-lily, "when there's anybody worth talking to."
One of the tools in your troubleshooting toolbox is the nameserver's debugging output. As long as your nameserver has been compiled with DEBUG defined, you can get query-by-query reports of its internal operation. The messages you get are often quite cryptic; they were meant for someone who has the source code to follow. We'll explain some of the debugging output in this chapter. Our goal is to cover just enough for you to follow what the nameserver is doing; we aren't trying to supply an exhaustive compilation of debugging messages.
As you read through the explanations here, think back to material covered in earlier chapters. Seeing this information again, in another context, should help you understand more fully how a nameserver works.
The amount of information the nameserver provides depends on the debugging level. The lower the debugging level, the less information you get. Higher debugging levels give you more information, but they also fill up your disk faster. After you've read a lot of debugging output, you'll develop a feel for how much information you'll need to solve any particular problem. Of course, if you can easily recreate the problem, you can start at level 1 and increase the debugging level until you have enough ...