How are subnets divided? Here s an example

1.The role of subnetting: reduce the broadcast domain.

3.Easy to manage.

In order to improve the utilization rate of IP addresses, the three categories of ABC addresses are divided into finer network segments by using masks, so as to save the waste of IP addresses as much as possible! Subnet division is to increase the broadcast domain and reduce the shadow or sock sound caused by the broadcast storm.

What is a subnet? a. A part of the network is a subordinate system of the main network B. A small network that operates in a larger network, which allows multiple types of devices to be connected to the network C. A division of the larger network to make it a smaller shard D. A smaller network, which maintains a database of all MAC addresses on the network Why should it be divided into subnets.

In order to improve the utilization rate of IP addresses, the three categories of ABC addresses are divided into finer network segments by using masks, so as to save the waste of IP addresses as much as possible!

Subnet division is based on taking away the host bit, and the part taken away is used as the subnet bit, and the subnet number and the broadcast address of each subnet occupy 2 addresses, so the subnet subnet will be divided and the host will be fewer.

Instead of increasing the number of available IP addresses, subnetting reduces the number of available IP addresses.

Subnet, the first time I heard of it, I don't know what a subnet is, I'm sorry, I can't help you solve this question.

Invincible algorithms.

Go and see it, and you'll understand.

All 0 all 1 don't need to subtract 2?

Then use the following ten.

Because it needs to be divided into 10 subnets, it must occupy 4 bits of the host number bit binary (because the 4-bit binary has 16 states, it is actually divided into 16 subnets), and its subnet mask is:

An IP address has a total of 32 bits (binary), in which some bits in the front represent the network number, and some bits in the back represent the host number, the number of network bits + the number of host bits = the number of IP address bits = 32, in short, the subnet mask is the number of bits of the network number, I will not understand, I can give an example:, this look at us we know the commonly used network segment of small companies, available IP address:, subnet mask:

The 24 after the slash refers to the network number, then obviously the available host number becomes 8 bits, then the number of available hosts is 2 to the 8th power - 2 = 254.

The method of calculating the subnet mask is: know the number of IPs in the subnet, find the number of bits of the host, and subtract the number of bits of the host with 32 to equal the number of bits of the network, that is, the subnet mask. Let's take the simplest example.

A Class C network includes 256 host positions, 256 is 2 to the 8th power, so the host bit is 8, then the network bit is 32-8=24, that is to say, the subnet mask is 24 bits, expressed in binary, converted to decimal is. Another example is a subnet divided by a class C network, the number of IPs of each network host is 32, and 32 is the 5th power of 2, so the host bit is 5, then the network bit is 32-5=27, that is to say, the subnet mask is 27 bits, which is expressed in binary, and converted to decimal is. Another example is a subnet divided by a Class B network, the number of IPs of each network host is 1024, and 1024 is 2 to the 10th power, so the host bit is 10, then the network bit is 32-10=22, that is to say, the subnet mask is 22 bits, which is expressed in binary, and converted to decimal system.

This material comes from ** 28 is wrong It should be 2 8 that is, 2 to the 8th power In addition, the host bit borrows the subnet division is also not correct Refer to the following.

For example, in a Class C network, there are 8 bits of hosts, 2 to the 8th power, that is, 256 host addresses, and the default subnet mask. Borrow 1 host bit to generate 2 subnets, each with 126 host addresses; Borrowing 2 host bits generates 4 subnets, each with 62 host addresses ......In each network, the first IP address (i.e., the IP address of all host parts) and the last IP address (i.e., the IP address of all host parts of 1) cannot be assigned to the host, so the number of available IP addresses in each subnet is the total number of IP addresses minus 2; According to the number of bits borrowed by the subnet ID, we can calculate the number of subnets, masks, and hosts per subnet, and the list is as follows: Number of subnets Number of subnets Subnet Mask (Binary) Subnet Mask (Decimal) Number of hosts per subnet 1 2 1 126 3 4 2 62 5 8 3 30 9 16 4 14 17 32 5 6 33 64 6 2 In the Class C network as shown in the table above, if the subnet occupies 7 host bits, there is only one host bit left, regardless of whether it is set to 0 or 1. Both mean that the host bit is either all 0 or all 1.

Since all 0 bits of the host represent the network, and all 1s are reserved as the broadcast address, there is no host address available in the subnet, so the host bits should be reserved at least 2 bits.