Chapter 15. Troubleshooting DNS

"Of course not," said the Mock Turtle. "Why, if a fish came to me, and told me he was going on a journey, I should say, `With what porpoise?' "

"Don't you mean `purpose'?" said Alice.

"I mean what I say," the Mock Turtle replied, in an offended tone. And the Gryphon added, "Come, let's hear some of your adventures."

In Chapter 12, we demonstrated how to use nslookup to make queries. In this chapter, we'll show you how to use nslookup—plus traditional TCP/IP networking tools like trusty ol' ping—to troubleshoot real-life problems with DNS.

Troubleshooting, by its nature, is a tough subject to teach. You start with any of a world of symptoms and try to work your way back to the cause. We can't cover the whole gamut of problems you may encounter on the Internet, but we do our best to show you how to diagnose the most common of them. And along the way, we hope to teach you troubleshooting techniques that will be valuable in tracking down more obscure problems that we don't document.