Hi friends, As some of you may know, I occasionally teach networking to college students and I frequently encounter misconceptions about some aspect of networking that can take a fair amount of effort to correct. For instance, a topic that has come up on this list before is how the inappropriate use of classful terminology is rampant among students, books and often other teachers. Furthermore, the terminology isn't even always used correctly in the original context of classful addressing. I have a handful of common misconceptions that I'd put on a top 10 list, but I'd like to solicit from this community what it considers to be the most annoying and common operational misconceptions future operators often come at you with. I'd prefer replies off-list and can summarize back to the list if there is interest. John