4) The network address and m

is divided into 4 segments with 8 bits each, and the segments are separated by periods. IP addresses can be divided into five categories: Class A, class B, class C, class D and class E. Commonly used are only class A, class B and class C. Class a address: the first 1 bits are 0, the last 7 bits are used to identify the network number, and the 24 bits are used to identify the host number. Class B address: the first 2 digits are 10, and the last 14 digits are used to identify the network numbe