TCP/IP Addressing
TCP/IP uses 32 bits, or 4 groups of numbers between 0 and 255, to address computers.
IP Address
Every computer must have an IP address to connect to the Internet.
Every IP packet must have an address in order to be sent to another computer.
In the next section of this tutorial, you will learn more about IP addresses and IP names.
An IP address contains 4 groups of numbers:
TCP/IP uses 4 groups of numbers to address computers. Each computer must have a unique 4-group address.
Each group must be between 0 and 255, separated by dots, e.g., 192.168.1.60.
32 bits = 4 bytes
TCP/IP uses 32 bits to address. A computer byte is 8 bits. So TCP/IP uses 4 bytes.
A computer byte can contain 256 different values:
00000000, 00000001, 00000010, 00000011, 00000100, 00000101, 00000110, 00000111, 00001000 ....... up to 11111111.
Now you should know why TCP/IP addresses are 4 groups of numbers between 0 and 255.
IP V6
IPv6 is short for "Internet Protocol Version 6", also known as the next-generation Internet protocol. It is a new IP protocol designed by the IETF (Internet Engineering Task Force) to replace the current IPv4 protocol.
We know that every host on the Internet has a unique IP address. An IP address is a 32-bit binary number representing a host number. But 32-bit address resources are limited and can no longer meet users' needs. Therefore, Internet research organizations have released a new host identification method, namely IPv6.
In RFC1884 (RFC is short for Request for Comments document. RFCs are actually standards for Internet-related services), the standard syntax suggests writing the 128 bits (16 bytes) of an IPv6 address as 8 16-bit unsigned integers, each integer represented by 4 hexadecimal digits, separated by colons (:), for example:
686E：8C64：FFFF：FFFF：0：1180：96A：FFFF
Colon hexadecimal notation allows zero compression, i.e., a string of consecutive 0s can be replaced by a pair of colons, for example:
FF05：0：0：0：0：0：0：B3可以定成：FF05：：B3
To ensure a clear interpretation of zero compression, the recommendation stipulates that zero compression may be used only once in any address. This technique is especially useful for the proposed allocation strategy, because many addresses will contain consecutive strings of zeros.
Colon hexadecimal notation can be combined with the dotted decimal notation suffix. This combination is especially useful during the transition from IPv4 to IPv6. For example, the following string is a valid colon hexadecimal notation:
0：0：0：0：0：0：128.10.1.1
In this notation, although each value separated by a colon is a 16-bit quantity, each dotted decimal part indicates the value of one byte. Using zero compression again yields:
：：128.10.1.1
Domain Name
12 Arabic numerals are hard to remember. It is easier to use a name.
A name used for a TCP/IP address is called a domain name. example.com is a domain name.
When you type in a domain name like http://www.example.com, the domain name is translated into numbers by a DNS program.
Around the world, a huge number of DNS servers are connected to the Internet. DNS servers are responsible for translating domain names into TCP/IP addresses, and for updating each other's systems with new domain name information.
When a new domain name is registered along with its TCP/IP address, DNS servers worldwide update this information.
Other Extensions