In the simpler days of 23 years ago (when I first started working with computers), I tried to know everything I could about hardware, OSs, and application programs. The reality of today's environment is that it's increasingly difficult to know everything about one program, much less about all the programs and services on a typical network. That reality means that you have to be more selective with your study and training time. Here are a few suggestions based on my efforts to come up to speed on Windows 2000.
First, look for the new features. Typically, software developers add new features either to enhance a program's functionality or to improve its performance. The problem with new features, though, is that not only can they introduce new bugs, but they can also break features that work in earlier versions. Vendors try to make their products compatible with earlier versions, but they don't always succeed. Training on the new features helps you foresee potential problems.
Knowing new features is also important if you're pursuing certification. Cisco, Microsoft, Novell, and Oracle recognize that new features cause headaches for the people who support their products. Thus, the certification exams focus more on what's new and less on what you should already understand. Certainly, a person new to networking needs to understand the basic concepts of how networks work; however, the Win2K MCSE core exams don't test your understanding of those concepts to any great degree. Instead, the exams focus on Active Directory (AD), DNS, and security. Friends who've taken the Novell certification exams over the past 10 years tell me that those exams also concentrate on what's new in each version.
Second, look for existing features or services that the vendor has modified to support the new features. DNS in Win2K is a good example because it has new functionality to support AD. Microsoft's decision to move from the computer naming convention used since Windows for Workgroups (WFW) to an Internet-style convention (e.g., www.windows2000mag.com) means that the DNS service has a greater role in a Windows network because it handles all searches for resources on the network. The end result is that administrators must plan for that increased dependency on DNS.
Third, find those features that have been de-emphasized in the new version. In Win2K, WINS is a good example because DNS replaces it. In fact, you can remove WINS from a network of Win2K-only computers. The main point, though, is that while WINS is an important service in Windows NT and the topic of many questions on the NT 4.0 certification exams, it's less important for a Win2K network administrator to know much about WINS. Knowing that fact lets you reallocate your training budget to classes that cover more important features.
Whatever role you play in your company, new features in the programs you use are going to affect your work environment. By focusing on learning those new features, you can be more efficient with your time, which is probably in short supply anyway.