Take a minute to imagine what would happen if the ISP that your company relies on informed you on July 5 that your Internet service would go dead on July 31. Imagine, as well, that many of your network administration employees were scheduled to take vacations that month. Next, imagine that the ISP you selected to replace your original provider told you as late as July 19 that it would not, in fact, be able to provide service to your area. Finally, imagine that the next ISP you turned to told you at 5:00 P.M. on July 31 that it had botched your new installation and would need another 5 days to install your service. Unfortunately, the scenario I've just described is my life for the past 3 weeks.

This experience has taught me, among other things, that both TCP/IP and the Internet have become crucial technologies in today's business world. As I write this, my customers can't interact with my company—they can't send me email, and they can't get information from my Web site. Moreover, my students can't get the files they need for their classes (fortunately, we aren't scheduled to launch our online training lineup for another few weeks). I'm sure that such downtime would have similarly drastic repercussions for your organizations.

Our dependence on the Internet is why network administrators must understand how TCP/IP and the Internet infrastructure channels information from point A to point Z. Such understanding means not only knowing how routers work but also how the underlying telecommunications networks transmit data. Developers also must know these technologies because the Internet is increasingly serving as the backbone for WANs.

Both VPN and Microsoft's .NET Framework technologies exist because using the Internet to connect companies with customers and vendors is far more cost effective than setting up private networks. However, these cost-saving solutions increase your exposure to failure points that lie outside of your realm of control. As I discovered last month, everyone's life becomes tremendously more difficult when the people who oversee those failure points lose their jobs.

Here's an exercise: Think of all the steps that you would have to take if your ISP or hosting company closed its doors. If your company is like mine, you host your own email, Web, proxy, and DNS servers, and you maintain several registered domain names. Be sure to consider that most domain-registration companies handle changes by email only. Assume that the technical contact for your domains can't help you because it, too, has thrown in the towel. Finally, assume that you will be changing all your IP addresses.

How you approach this exercise will give you some insight into your understanding of TCP/IP. Remember, if you don't know TCP/IP and all the services that accompany it, you'll likely fail the MCSE exams. However, as my troubles illustrate, passing the exams is a secondary concern. If you fail real-life tests like the one I've endured for 3 weeks, it's your company and your career that will suffer.