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IP Addresses

IP addressing is used to identify each host on a network. A host can be a computer, server, printer, any device that is connected to the network.

IP addresses are similar to phone numbers in that each identifies a unique host on a network as a phone number identifies a single phone on the phone network.

As each phone number is divided into parts (312) 555-1212

(312) Area Code Identifies the network the phone is on. In this case it represents a phone on the Chicago network.

555-1212 Identifies an individual phone or hosts on the network.

IP addresses have two main parts. The Network and the Host parts.
Subnet Masks

The subnet mask identifies the network and hosts portions of the IP address.

In Binary (1,0) the subnet mask is very simple. There are 4 octets to the subnet mask just as there are to an IP address. In the subnet mask the value of 1 (one) represents the network portion and 0 (zero) represents the host portion.


Represents the first 8 bits as network bits and the last 24 bits as host bits. There are 3 major classes of IP addresses Class A, Class B and Class C. There are D and E classes for later discussion.

IP Default Address Classes

Each Address consists of 4 Octets. Even though most IP addresses are written in Dotted Decimal notation. The addresses were designed to be seen in binary.

The Class of address is determined by the first Octet.

Subnetting Resources
Subnetting Practice:
Excel Spreadsheet format

Subnet Excercise #1
Subnet Excercise #2
Subnet Excercise #3
Subnet Excercise #4
Subnet Excercise #5
Subnet Excercise #6
Subnet Excercise #7
Subnet Excercise #8
Subnet Excercise #10

Cisco IP Subnetting Guide-PDF

IP Addressing and Subnetting Workbook-PDF
© 2006 Steve Hyzny. All rights reserved.