I was reading the book, CCENT/CCNA ICND1 Official Exam Certification Guide  by Wendell Odom. In Chapter 4, he discusses how IP defines three different network classes for addresses:  Class A, B and C. I understand that Class A, B, and C networks each have different length for the part that will identify the network. So, a Class-A network has a 1-byte long network part and 3 bytes for the rest of the address. Similarly, a Class B network has a 2-byte long network part, leaving 2 bytes for the host portion of the address and a Class C network has a 3-byte long network part, which leaves only 1 byte for the host part.


My confusion arose when I reached to this table:




I am not able to figure out how he pulled those numbers from (27, 214, and 221)? Shouldn’t the numbers be 28  for Class A as it has 1-byte long network part, 216 for Class B as it has 2-byte long network portion and 224 for Class C as it has 3-byte long network portion. There is no mention of these numbers in the book and I somehow can’t figure out how to come up with those numbers. I would appreciate if any of you could provide me with an explanation?