Ok, I was critical when I ordered this book - teach anything in 24hours? But I was very pleasantly surprised upon first opening the book. Already having worked with TCP/IP for some time, but wanted to fill in gaps in knowledge base, this book has served it's purpose perfectly, written by someone obviously on top of their game, the book starts by letting the reader know exactly the format of the book from that point on and describes all aspects in just enough relevant detail for that chapter. Summaries at the end of each chapter help to reinforce the learning, and although I found the book dwelled on the hours aspect an awful lot - the book is all about learning in 24hours after all. As opposed to chapters, the book deals in hours, by the end of hour one, you should have an understanding of the very basic elements of TCP/IP, Hour 2 goes deeper and so on, the text always refers to learning more in detail in hour x..., once you get used to that it's a very well written book that fulfills its mission perfectly. Ideal for the beginner and intermediate user. very pleased with this purchase !