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Aolynk DR811/DR814 ADSL2+Broadband Router 6 IP Addresses, Network Masks, and Subnets
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6 IP Addresses, Network Masks,
and Subnets
6.1 IP Addresses
& Note:
This section refers 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.
IP addresses, the Internet 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.
l Network ID: Identifies a particular network within the Internet or intranet
l 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 (refer
to the following section). Table 7-1 shows the structure of an IP address.