Learn Windows XP Professional in 15 Minutes a Week: TCP/IP Addressing in Windows XP Professional

Welcome to
this week’s installment of Learn Windows XP Professional in
15 minutes a week, the 13th in this series. This article
will continue covering the TCP/IP Protocol within Windows XP
Professional with a specific focus on administration and
management of the network protocol under Windows XP
Professional.

Jason Zandri’s latest article in the Learning Windows XP Professional in 15 Minutes a Week series covers the TCP/IP Protocol with a specific focus on administration and management of the network protocol under Windows XP Professional.

Internet Protocol Addressing Overview

The
Transmission Control Protocol/Internet Protocol is a network
communication protocol. It can be used as a communications
protocol on private networks and is the default protocol
in use on the internet. When you set up any system to have
direct access to the Internet, whether it is via dial-up or
one of the high speed technologies in use today, your system
will need to utilize the TCP/IP protocol (whether it is a
Windows-based system or not).

Also, if the given system needs to communicate with other
TCP/IP systems on the local LAN or WAN, it will need to
utilize the TCP/IP protocol as well.

[NOTES FROM THE FIELD] –
This is just a basic overview of TCP/IP, and I didn’t want to get too involved
with it within this article. There is bountiful
information on TCP/IP all over the internet and before
pouring through the RFCs I would first suggest you try these two resources —
TCP/IP
Frequently Asked Questions or

TCP/IP Protocol Suite – Questions & Answers.

I have gone into a more detailed
overview of the TCP/IP Protocol in last week’s article, which covered the four-layer conceptual model of TCP/IP and how the model stacks up against the seven layer Open System Interconnection (OSI) protocol model.

TCP/IP
version 4 (IPv4) addresses are made of up four 8-bit fields
(octets) and are 32-bits in size total. Microsoft TCP/IP
version 4 supports the standard classes of address, which
defines which bits are used for the network ID and which
bits are used for the host ID. There are five TCP/IP version
4 (IPv4) addresses, although for the most part, only the A,
B, and C classes are used. The system of IP address classes
described here form the basis for IP address assignment.
Classless Inter-Domain Routing (CIDR) addressing is now
being used more often, and I will cover that later in the
article. Classless Inter-Domain Routing is making the IP
address classes in their current form “less defined”, for
lack of a better term. Still, the classes form the base of
any addressing scheme.

TCP/IP
version 4 addresses are made of both a network ID and a host
ID. The network ID address identifies the physical network
where the hosts exist. The host ID address identifies the
individual TCP/IP host on a network. The host ID must be
unique on the internal network; that is, no two nodes on a
given network can have the same network ID AND host ID.

[NOTES FROM THE FIELD] –
You can have two hosts with the IP host name of 112.12.44
if one is on network 10 and another is on network 11. (The
full IP addresses of these hosts would be 10.112.12.44&
and 11.112.12.44. The subnet mask would be 255.0.0.0.) You
cannot assign both of these nodes the host address of
112.12.44 if they are both on network 10 or both on network
11.

The
“division” point between the network ID and the host ID is
called the subnet mask. The subnet mask is used to determine
where the network number in an IP address ends and the node
number in an IP address begins.

The bits in a subnet mask are set consecutively from left to
right and there can be no “skips” in the setting structure.
The subnet mask of 255.255.128.0 is valid because all eight
bits are set in the first two octets and the first bit of
the next octet is also set.
(11111111.11111111.10000000.00000000). The subnet mask of
255.255.64.0 is not valid because there is a “missing” bit
that is not allowed. (11111111.11111111.01000000.00000000).

[NOTES FROM THE FIELD] –
The left most bit in a
TCP/IP version 4 address is called the Most Significant Bit
(MSB) and has the highest value. The right most bit in a
TCP/IP version 4 address is called the Least Significant Bit
(LSB) and has the lowest value.

I have detailed subnet masks
in a little more detail in the following section.