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how to understand this IP address (and all the others)

27 mayo, 2021

Every website, every computer and every router has an IP address, that’s the way they can be identify themselves within a network or on the Internet. IP addresses can change constantly, so if we have to compare them with something it could be with our home address, which changes if we move. If someone wants to send us something, they need our address, and if a device wants to communicate with another and send data to it, they need their IP.

In the case of is an address that is well known to users, and it should be familiar to anyone who has ever used it to access the configuration of their router. This IP is a private address used by most router manufacturers from which the device settings can be accessed. If you want to know why that one is used specifically and not another, understand how IP addresses work and know some other equally famous, keep reading.

Private IP addresses and why

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In your home network, it is your router that assigns an IP address to your computer and the rest of your devices. If you wonder how to ensure that the IP of your PC is not the same as some other on the Internet, it is because there is a list of numbers that are reserved for private use, whether at home, in the office or in a company. is one of those private addresses that is never used for a public website.

Private IP addresses do not belong to anyone, and any organization can use them without approval or registration, but these addresses cannot transmit over the public internet.

Understanding how the numbers of each IP are used is quite intricate, but the ranges they cover are somewhat simpler. There are three classes of private IP addresses and they cover about 18 million IP address numbers in total:

  • Class A: ranging from to
  • Class B: ranging from to
  • Class C: ranging from to

Class A is the class for very large networks, such as those of an international company. Class B’s are for medium-sized networks, such as a university network. Class C IP addresses are typically used for smaller networks. falls within the smallest private address space (between and Note that the Class C IP range starts at and that the IP address of your router is a very close number to this, a very low number in that special range.

Router Login

Using this address as a standard is quite convenient although it is not a rule. It makes it easy for us to access the configuration of a router either at home or anywhere else. Depending on the brand of the device, the page that appears will be different, in some cases it asks for a username and password that are usually quite generic and that you can find out in the manual of your equipment or on the Internet. You can always change them later.

Not all manufacturers use this address, but normally, and are the most common. However, you may find that some computers use numbers in the Class A and Class B ranges, such as or Here you can find a list of the most common IP addresses used by different router manufacturers.

The IPs are over and we multiply them like bread and wine

Ipv4 Ipv6

Although all IP addresses are a number that identifies a device and they all do so in a logical and hierarchical way, they are not all the same. Initially the IP Protocol defined IP addresses as a 32-bit number: the well-known IPv4 that is still in use but should go out. With the gigantic growth of the Internet and the depletion of available addresses, a new protocol was created: IPv6, which uses 128 bits for addresses, many, many more millions of available IPs.

Each IPv4 address consists of 4 octets of 8 bits each. For example, Class A addresses have a first octet from 0 to 127 and the other three octets are used to identify the host. That means there are 126 Class A networks with 16,777,214 possible hosts for a total of 2,147,483,648 unique IP addresses. IPv4 has a total of 4,294,967,296 addresses encoded in 32 bits and as we already know a portion dedicated to private networks. Or whatever, my head has started to hurt.

IPv6 addresses are 16 octets instead of 4, consist of 128 bits, and are expressed in 32-digit hexadecimal notation. IPv6 currently allows every person on Earth to be assigned several million IPs. In total it covers 40,282,366,920,938,463,463,374,607,431,768,211,456 of available IP addresses. My head hurts again.

There is no place like home. Another rather interesting address is, the local loop address or loopback. It is the IP that your computer uses to talk to itself.

The IP refers to the localhost, that is to say to the local host, that is to say to the PC you are using. It can be used to locate a fault, to test the network, or to access a web service that has been installed on the computer itself.

Network standards IPv4 mostly use address as loopbackTherefore, addresses are reserved to designate the machine itself. In 1981, 0 and 127 were the only reserved class A networks. 0 was used to point to the local host and that left 127 for the local loop.

The logic behind this is that 127 is the last number in a class A network. is the first assignable number in the subnet. In binary 127 it is is 01111111, which makes the address “very easy to remember”. IPv6 instead uses :: 1 or 0: 0: 0: 0: 0: 0: 0: 1, an address that for many makes more sense because it is much easier to remember.

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