CodePudding user response:
The topic of is not very strict, dividing branch, in every division, the division of the number of each subnet an IP address is the same, for a class C IP address, a total of 256 IP address, host asked subnet number not less than 100, then the IP address of the subnet number is 128, is divided into two subnets, the address bits borrowed one to do network who is up to 10000000 (borrow), mask is 255.255.255.128,So the topic is not only closely, after dividing branch first subnet (0 subnet) and finally a subnet (full 1 subnet) cannot be used, since due to the development of technology, the zero subnet or full 1 subnet can recycling (which is a specific forgot), now the technology is used the two subnets can be recycled? Need to check information, even if you can use, in the actual project to consider whether hardware support,
The first per subnet an IP address and the last 1 1 IP is not allowed to use the
So according to the traditional way of speaking, for A subnet A, N host with A subnet, divided into the subnet not borrow one, don't borrow N - 1, such as class C address has eight host, do not borrow one, also don't borrow seven,