It is to this third group that I address this column.

Economists have a rule called the Law of Diminishing Returns. It says that after a certain point, the returns decrease from the input of each additional factor. For example, on a hot day, each successive drink after the first satisfies your thirst less and less, and soon you stop drinking.

This rule also seems to apply to certifications. I have learned over time in managing my own credentials that, after a certain point, the benefits from each additional certification decreases, and eventually turns to zero. I also believe one can argue that the value from these additional certifications may be negative -- that is, it may actually be detrimental.

Completing a premium certification such as Microsoft's MCSD, MCSE, Novell's CNE or even Cisco's CCIE is a major career achievement. However, many then move on to lower-level certifications of lesser value. This can put you at risk of being distracted from your core specialty areas -- after all, even with the best will in the world, we only have so much time available to learn and so many brain cells to store all of this!

I made the mistake of over-certifying earlier in my career. Soon after I completed the MCSE, I completed MCSD, and then took all of the other exams for all the then-current BackOffice products. This was useful to give some background information on these products, but other than SNA Server and the base Windows NT operating system, I couldn't really say I was an expert in any of them. It was an interesting intellectual exercise every few weeks to prepare for and take all of these exams, but it didn't really prove anything. Worse still, with product upgrades and recertification requirements coming thick and fast, I was later either going to have to keep pounding away on the exam treadmill -- to prove what, exactly? -- or make some decisions on what exams to pass on. Now, of course, in the Microsoft program electives don't expire, and knowing a little about SMS 1.0 or Visual Basic 3.0 is not of much use to anyone.

Along these lines, I receive e-mails from folks who sign their name as something like "John Doe, MCP, CNA, CCNA, A+, Network+, Server+, I-Net+". All of those minor certifications are useful for picking up entry-level skills in a variety of areas, but when all of these are put together it doesn't equate to the value derived from a single major certification. What the string of certifications can show is a lack of focus and depth. It's great to have a broad general knowledge in IT, but what we all need to be considered an expert in something -- that's how we get hired.

Don't get me wrong -- I'm not saying that learning is bad and you should burn all of your books. But you need to make a clear and rational choices in certification, rather than simply wondering what certification you should get next. As you can see from above, there are often good reasons for NOT taking that next exam.

What do you think? What is the ideal amount of certification? Let me know by adding your comments below.