How to determine a CIDR block from an IP address

This is a Class B IP address.

30 is the network identity.

The first 30 bits of the IP into binary are the network address, that is, the network segment where it is located.

So the network segment is.

That is, he includes 4 IP addresses.

The first 30 bits are the network address, and only two bits are used to allocate the number of hosts.

2 times 2 is 4, which means that only 4 IP addresses can be assigned.

IP address has.

1. Only according to the IP to judge the network segment according to the numerical range of the first set of numbers;

2. According to the current IPv4 standard, the default value range of the first group of Class A addresses is 1-126, the first group of Class B addresses is 128-191, and the first group of Class A addresses is 192-223.

3. Then the default mask of Class A address is, Class B, Class C;

4. For example, if it is judged to be a Class C address, its network segment is:

This is a network segment. It's clear. The address you use is the B segment of the address, including . All the way up to 30

If I don't know the IP address allocation of an intranet, what command can I use to find out?

Here's how it is judged:

There are generally three types of addresses that are commonly used.

1. A Class A IP address consists of a 1-byte network address and a 3-byte host address, and the highest bit of the network address must be "0", and the address range is from to. There are 126 Class A networks available, each capable of accommodating more than 100 million hosts. It should be noted that the network number cannot be 127, because the network number is reserved for circuit and diagnostic functions.

2. Class B IP address.

A Class B IP address consists of a 2-byte network address and a 2-byte host address, with the highest digit of the network address having to be "10" and the address range from to to. There are 16,382 Class B networks available, each capable of accommodating more than 60,000 hosts.

3. Class C IP address.

A Class C IP address consists of a 3-byte network address and a 1-byte host address, and the highest bit of the network address must be "110". There are more than 2.09 million networks ranging from to class, and each network can accommodate 254 hosts.

<> first method:

1. Open the "Start" menu of the computer and select the "Run" option;

2. Then enter the command "cmd" after the opening of the "Run" box, and then, click the "OK" option below to open the "cmd" command runner;

3. In the "cmd" command operation box that opens, enter the command "ipconfig", after the input is completed, press the enter key to run, and you can find the local IP address CIDR block.

The second method:

1. Right-click on the network icon in the taskbar in the lower right corner of the computer, and click the "Network Settings" option in the pop-up menu;

2. Manually scroll to the bottom of the page and click "Open".

Tools Raw Materials:

ASUS redolbook14

windows 10

Huawei Mate40

emui12

Browser 2019

1. Method 1, directly check the label at the bottom of the router, the router tab page will generally provide the default IP address, user name and password, some provide IP address, some provide web address, can be accessed.

2. Method Qi Ran two, check it on the mobile phone settings. Go to the "Settings" page and click "Wireless & Network".

3. Click "Wi-Fi".

4. Click "High Stuffiness Configuration" to directly check the "IP address".

5. Method 3, check on the computer, open the computer's "Start Run" or use the shortcut win+r, enter cmd in the running window, OK.

6. Enter the command prompt window, enter ipconfig, and press the enter key to execute.

7. Display a piece of information, in which the IP address is the IP address of the machine, and the default gateway is the router address we want to query.

How to determine whether two IP addresses are in the same network segment?

To determine whether the two IP addresses are in the same network segment, their IP addresses are respectively compared with the subnet mask, and the result is a network number, if the network number is the same, it is in the same subnet, otherwise, it is not in the same subnet.

The result of the WITH is:

The result of the WITH is:

It can be seen that the result (which is the network address) is the same, so it can be judged that the two IP addresses are in the same subnet.

Step 1, translate the IP address to binary 11000000

Step 2, convert the subnet mask to a binary 11111111

In the third step, the above two binary number logic is combined with (and), and the result is the network part. “11000000

00001101" and "11111111

00000000" and "get 110000000".

00000000", that is", this is the network number of this IP address, or "network address".

Step 4: After inverting the binary value of the subnet mask, and then perform the AND (and) operation with the IP address, the result is the host part. For example, replace "00000000

11111111 (the value of the subnet mask) is inverse to 110000000

00001101 "000000000" is obtained after performing and arithmetic

00001101", i.e., ", this is the IP address host number (which can be shortened to "13").

Three of the host bits are classified as "network identification numbers", because the network identification numbers should all be "1", so the byte segment corresponding to the host number is "11100000". After converting to decimal to 224, this finalizes the subnet mask. If it is a Class C network, the subnet mask is; In the case of a Class B network, the subnet mask is; If it is a Class A network, the subnet mask is.

In this case, the CIDR block of the IP address is related to the subnet mask. The IP address is a 32-bit binary number, and the subnet mask is the same, which is a 32-bit binary value. Usually the value of the subnet mask is how many bits are 1 in front and 0 in the end.

For example, this subnet mask is 1 for the first 24 bits and 0 for the last 8 bitsWhen distinguishing network segments, match the IP address and subnet mask so that when there is a numeric value, the same value is the same CIDR block.