Till now we have described common DNS functions that every DNS implementation should support. On the contrary, DNS extensions are other optional DNS functions. It is up to each particular application to choose which of them it will support and which not. For example, the DNS Update extension is widespread because of its successful implementation in Windows 2000 and consequently in the Windows 2003 operating system.

This book contains a lot of examples to demonstrate the functionality. All the given examples may not work by the time you read this book. Some of them would demonstrate negative output and some of them would demonstrate some specific parts of output. Sometimes you can get similar output, if you use new URLs.