Who knows how IP address segments are divided?

Class A: Class B:

Class C: Class D:

All 0s in the network field of a Class A IP address mean "this network (Class A network)" and is not assigned to a specific host. All 1 in the IP address indicates a local loopback address, which is used to test the communication between processes on the host, that is, the IP address with network number 127. The host number of a Class A address is 3 bytes, so the maximum number of hosts that can be connected to a Class A network is:

2^24-2。All 0 host numbers represent a single network address (a Class A network) to which the host is connected, and all 1 host numbers represent all hosts in the network.

The network number of a Class B address occupies 2 bytes and can only be used with 14 bits. The Class B network number that can be assigned is 2 14-1 (no, the smallest network number is:. The maximum number of hosts that can be connected to each Class B network is:

2^16-2=65534。(Deduct all 0 and 1 IP addresses of the host number).

The network number of a Class C address occupies 3 bytes and can only be used with 21 bits. The Class C network number that can be assigned is 2 21 (not used), and the smallest network number is: . The maximum number of hosts that can be connected to each Class C host is:

2 8-2 = 254 (minus IP addresses with host numbers of all 0 and all 1).

1. Each IP address is composed of two parts: network number + host number. In this sense, an IP address is a hierarchical address structure.

Benefits of grading:

A. When the IP address management agency assigns the IP address, it only assigns the network number, and the remaining host number is assigned by the unit that obtains the network number. This makes it easy to manage;

b. The router is only grouped according to the network number connected to the destination host (the host number is not allowed to be considered), so that the number of items in the routing table can be greatly reduced, thereby reducing the memory occupied by the routing table, and checking the time used to find the route.

2. In fact, an IP address is used to identify the interface of a host or a router or a link. When a host is connected to two networks at the same time (e.g., a lab's server).

The host must have two corresponding IP addresses, which means that it must have two NICs.

3. The switch is a device on the data link beam and layer, and the hosts connected with it still belong to the same network. The hosts of different LANs must be connected through routers due to different network numbers.

4. All network numbers are equal.