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# TCP/IP Addressing * * * TCP/IP uses 32 bits or 4 sets of numbers between 0 and 255 to address computers. * * * ## IP Address Each computer must have an IP address to connect to the Internet. Each IP packet must have an address to be sent to another computer. In the next section of this tutorial, you will learn more about IP addresses and IP names. * * * ## 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 of numbers must be between 0 and 255, separated by dots, such as: 192.168.1.60. * * * ## 32 Bits = 4 Bytes TCP/IP uses 32 bits for addressing. One computer byte is 8 bits. So TCP/IP uses 4 bytes. One computer byte can contain 256 different values: 00000000, 00000001, 00000010, 00000011, 00000100, 00000101, 00000110, 00000111, 00001000 ....... up to 11111111. Now, you should understand why TCP/IP addresses are 4 groups of numbers between 0 and 255. * * * ## IP V6 IPv6 is the abbreviation of "Internet Protocol Version 6", also known as the next-generation Internet protocol. It is a new IP protocol designed by the IETF group (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 uses a 32-bit binary number to represent a host number, but the 32-bit address resources are limited and can no longer meet user demands. Therefore, Internet research organizations have released a new host identification method, namely IPv6. In RFC1884 (RFC stands for Request for Comments document. RFCs are actually some standards related to Internet services), the standard syntax suggests writing the 128 bits (16 bytes) of an IPv6 address as 8 16-bit unsigned integers, each represented by 4 hexadecimal digits, separated by colons (:), for example: 686E:8C64:FFFF:FFFF:0:1180:96A:FFFF The colon hexadecimal notation allows zero compression, where a sequence of consecutive zeros can be replaced by a pair of colons, for example: FF05:0:0:0:0:0:0:B3 can be written as: FF05::B3 To ensure a clear interpretation of zero compression, it is stipulated that in any address, zero compression can only be used once. This technique is particularly useful for the proposed allocation strategy, as many addresses will contain consecutive zero sequences. The colon hexadecimal notation can be combined with dotted decimal notation suffixes. This combination is particularly useful during the IPv4 to IPv6 transition phase. 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 specifies a byte value. Using zero compression gives: ::128.10.1.1 * * * ## Domain Name 12 Arabic numerals are hard to remember. Using a name is easier. The name used for a TCP/IP address is called a domain name. is a domain name. When you type a domain name like 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.