Why do LAN IPs usually start with 192.168 instead of 1.2 or 193.169?

The LAN IP usually starts with 192.168. This is due to the manufacturer of the router.

## People who configure routers often The router's default IP address will be used as the gateway. Changing it to another IP address is both confusing and troublesome. Don’t believe it yet, people who often do network maintenance set up IP addresses and entered “192.168” very smoothly. But this is not the root cause.

The early broadband access methods generally used coaxial cables. The earliest NAT gateway equipment (the gateway is like the door to the home, and the IP address is the house number). The default IP address is 192.168.0.1, so The user's gateway here can only use 192.168.1.1.

In order to facilitate maintenance and after-sales service, router manufacturers set 192.168.1.1 in the router by default, thus avoiding 192.168 .0.X this network segment. Setting the IP address starting with 1 is just to avoid wasting IP addresses.

The LAN IP address usually starts with 192.168. It is really just a habit. 192.168 is not the only choice for setting the LAN IP address. Many enterprises choose to start with 10. or 172.16 to plan their LAN.

#Composition of IP address

For computers and network devices, IP addresses, like other data, are composed of binary numbers such as 0 and 1. The IP address is composed of 32 Composed of 4 bits of binary, converting 4 segments of decimal numbers is just for the convenience of human beings to distinguish and use.

For example, 1111 1111 in the secondary system is converted to decimal 255.

牛逼啊！接私活必备的 N 个开源项目！赶快收藏

The IP address of IPV4 adopted "hierarchical addressing" in 1993, dividing IP addresses into A, B, C, and D , E five categories, the address of each category is identified by their first 3 digits. Type A is generally used for governments, type B is generally used for companies, type C is generally used for sharing, type D is generally used for anchors, and type E is generally used for experiments.

In fact, before IP address classification, there was no subnet mask. A 32-bit IP address is composed of an 8-bit network address (specified which network the host is connected to) and the "remaining" host bits (which specify the host's address within that network). Assigning IP addresses in this way was feasible before the advent of LANs, because there were only a few larger networks (ARPANET). However, in the early days of the emergence of local area networks, it was already apparent that they were not sufficient, so they were classified and masks were introduced.

Nowadays, a complete IP address is inseparable from the mask. The IP address and the subnet mask perform a bitwise AND operation to obtain the subnet address. Every IP address is divided into two parts, the network address and the host address. The purpose of this is to make it easier to address when the router forwards the data packet.

for example:

Letters and packages from the same province are often put together, and then those from the same city in the same province are put together for delivery. The delivery person who makes the final delivery only needs to look at the street and house number. The router first looks at the network address of the destination IP in the data packet, sends the data packet to a certain network, and then finds the destination host from the network based on the host part of the destination IP in the data packet. So we can think of network address = network number, host address = host number. This is the true meaning of "hierarchical addressing" of IP addresses.

Why do LAN IP addresses like 10.X.X.X, 176.16.X.X and 192.168.X.X appear?

That’s because there was already a shortage of IPv4 addresses as early as the mid-1990s. So someone started thinking: IP addresses cannot be repeated. Repeating them means that the data will be sent incorrectly. However, you can determine a private domain IP address for everyone to use within the LAN for free. These private domain IP addresses can be reused in different LANs, as long as you ensure that there are no duplicate IP addresses in the same LAN. NAT technology (Network Address Translation) was born in this scenario. In addition, search the public account's top algorithm backend to reply "Algorithm Experience" to get a surprise gift package.

This is like a program-controlled telephone. You first dial a phone number that can be connected normally, and then the program-controlled switch transfers the extension number. NAT technology acts like a program-controlled switch. This greatly alleviates the problem of IP address exhaustion.

So among the five types of IP addresses, class A, B, and C addresses are divided into private IP addresses for everyone to use for free. By default, home routers start with 192, because the number of IP addresses required in a subnet does not require many; and those starting with 10 and 17.16 are generally used in enterprises because there are many IP addresses that can be allocated. In addition, there are some special IP addresses, such as: 0.0.0.0 can only be used as the source address; 255.255.255.255 is the broadcast address; 127.x.x.x is the loopback address for local use.

Summarize

## It is not so much that the current LAN IP usually starts with 192.168 instead of 1.2 or 193.169, because of network technology the result of evolution. The editor is more willing to believe that this is due to people's habits. This is just like how we walk or drive on the right now. If one day it is required to drive on the left, then every city will definitely be in chaos. Traffic regulations are also based on the original public trust before they can become effective regulations. The same is true for IP address planning.

The above is the detailed content of Why do LAN IPs usually start with 192.168 instead of 1.2 or 193.169?. For more information, please follow other related articles on the PHP Chinese website!