Featured Opinion:
Network Troubleshooting 101 – Part 1

By Dave Kleiman, CastleCops Staff Writer
Technical Editor Bill_Bright
July 14, 2005

Suddenly you lose your Internet connection, what do you do?

I know many people come to CastleCops (CC) to find the answer. Here we will learn how to check our basic network information and network connectivity. This will prepare you to answer questions your CC Staff member may have.

You may wonder why the CC Staff asks you to step through certain things. We will attempt to enlighten you on why we need certain information. Along with the article, we will provide MyNetwork.exe. This tool is used to create an output file called MY_Network_Info.txt. It will contain the network information for that computer and may be uploaded to CastleCops.com for analysis by a CC Staff member if you are having network connectivity issues.

Let us take step back in time. Although, we are looking at this from a troubleshooting perspective, we should keep track of our basic network information and view it on a regular basis.

Part -1 will cover:

NIC/Adapter configuration
Network configuration
Network connectivity

Many of these areas are interlaced, therefore the information we address in any one part may cover all three areas.

The information we will cover pertains to Windows® 2000/XP/2003 Operating Systems. If an operating system (OS) has unique requirements, they will be addressed individually.

We will be utilizing the Command Line Interface (CLI), sometimes referred to as the Command prompt window, Command window, or the Command shell. We get there by selecting Start | Run and typing cmd.

Since we will be utilizing the CLI and looking at a lot of information, we will customize the CLI allowing us to perform our tasks a little easier.

Right Click on the Title Bar of the CLI and select Properties.

On the Options tab, in the Command History box, increase the Buffer Size to 500 and the Numbers of Buffers to 5. In the Edit Options box, Select (Check on) the Quick Edit Mode and Insert Mode.



On the Layout tab, in the Screen Buffer Size box, increase the Width to 100, and Height to 2000. In the Windows Size box, change the Width to 100, and Height to 50-70.



Select OK | Select “Save properties for future windows with the same title” | Select OK



Commands we will be utilizing:

IPCONFIG PING TRACERT PATHPING ROUTE NSLOOKUP

Note: We will be using the generic term Internet Connection Sharing (ICS) Equipment. When we use the ICS Equipment term, we are referring to any Router, Cable/DSL Modem etc. that provides you with Network Address Translation (NAT). NAT allows multiple computers on a network to share a single internet connection using one IP address. NAT is a commonly used IP translation technology and utilized by the most common ICS Equipment. Microsoft has built their ICS around it and almost every Cable/DSL Broadband Router uses it.

Let us dive in headfirst and begin looking at our network configuration.

What is IPCONFIG, and how does it work?

IPCONFIG is the command line utility that is the starting point for identifying Transmission Control Protocol / Internet Protocol (TCP/IP) Network and Network Interface Card (NIC) configuration information/errors, and gives us a glance into what may be causing connectivity issues. We will append the /? argument or switch to the end of the command to identify the arguments available. (Note: appending the /? or /help argument is available with most command line commands.)

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