网络子网掩码详解(局域网络分割)（国外英文资料）.docVIP

网络子网掩码详解(局域网络分割)（国外英文资料） An overview of the subnet mask The concept of a subnet mask Subnet mask is a 32-bit address, used for shielding to distinguish the network id and host IP address part of the logo, and indicate that the IP address is on the LAN, or on a remote network. Determine the subnet mask number The number of digits for the subnet mask is determined by the number of possible subnets and the number of hosts per subnet. Before defining the subnet mask, you must know the number of subnets and the number of hosts used. The steps to define a subnet mask are: A, determine which group addresses we use. For example, the network number we applied to is 210.73.a.b, the network address is c class IP address, the network is 210.73, and the host is a.b. B, according to the number of subnets we need now and the number of subnets that may be extended in the future, use some bits of the host machine to define the subnet mask. For example, we now need 12 subnets, maybe 16 in the future. Use the first four bits of the third byte to determine the subnet mask. The first four bits are 1, the third byte 11110,000, which we call the new binary subnet mask. C, every bit of the corresponding initial network set to 1, namely the first two bytes are set to 1, 4 bytes are set to 0, the subnet mask of binary form is:1111111100000000 D, convert this number to a broken decimal form: 255.255.240.0. This number is the networks subnet mask. The IP mask is labeled The notation of A and no subnets The IP address of a subnet can be written as a mask with a host number 0. As IP address 210.73.140.5, the mask is 255.255.255.0, or the default mask, only the IP address. B, the notation for the subnet When there is a subnet, be sure to pair up. Take the C class address as an example. The first three bytes in the IP address represent the network number, and the second byte indicates the subnet number and the host number, indicating whether the two IP addresses belong to a net