6 ip addresses, network masks, and subnets, 1 ip addresses, 1 structure of an ip address – Asus GigaX2024X User Manual

Page 101: Ip addresses, network masks, and subnets, Ip addresses, Structure of an ip address, 6ip addresses, network masks, and subnets

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GigaX Series L2 Managed Switch User Guide

6

IP Addresses, Network Masks, and
Subnets

6.1 IP

Addresses

This section pertains only to IP addresses for IPv4 (version 4 of
the Internet Protocol). IPv6 addresses are not covered.

This section assumes basic knowledge of binary numbers, bits,
and bytes. For details on this subject, see Appendix 6.

IP addresses, the Internet's version of telephone numbers, are used to identify
individual nodes (computers or devices) on the Internet. Every IP address
contains four numbers, each from 0 to 255 and separated by dots (periods),
e.g. 20.56.0.211. These numbers are called, from left to right, field1, field2,
field3, and field4.

This style of writing IP addresses as decimal numbers separated by dots is
called dotted decimal notation. The IP address 20.56.0.211 is read "twenty dot
fifty-six dot zero dot two-eleven."

6.1.1

Structure of an IP address

IP addresses have a hierarchical design similar to that of telephone numbers.
For example, a 7-digit telephone number starts with a 3-digit prefix that
identifies a group of thousands of telephone lines, and ends with four digits that
identify one specific line in that group.

Similarly, IP addresses contain two kinds of information.

Network ID

Identifies a particular network within the Internet or intranet

Host ID

Identifies a particular computer or device on the network

The first part of every IP address contains the network ID, and the rest of the
address contains the host ID. The length of the network ID depends on the
network's class (see following section). Table 7 shows the structure of an IP
address.

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