Troubleshooting Network Problems : Working with Network Diagnostics

If you suspect you’re having network trouble—such as computers on the network not being able to see each other or file transfers or other network activity behaving erratically—but you aren’t sure, one easy way to find out is to run the Network Diagnostics utility. This is a Help and Support Center connectivity troubleshooting tool that can help you isolate network problems.

To get started, use any one of the following techniques:

• In the Network Connections window, click the task pane’s Network Troubleshooter link, and then click the Diagnose Network Configuration and Run Automated Networking Tests link.

• Select Start, Help and Support, click Fixing a Problem, click Networking Problems, and then click the Diagnose Network Configuration and Run Automated Networking Tests link.

• In the System Information utility (Start, All Programs, Accessories, System Tools, System Information), select Tools, Net Diagnostics.

• In a Command Prompt window, enter the following command:

  								netsh diag gui

Network Diagnostics operates by performing three different actions:

Ping	Pings various objects to check for basic connectivity. For example, Network Diagnostics pings the loopback address (127.0.0.1), your IP address, the default gateway, the DHCP and DNS servers, and more.
Connect	Attempts to connect to certain servers, such as your Internet mail and news servers.
Show	Displays information about various objects, including your network adapters, network clients, DHCP servers, IP addresses, modems, and more.

Setting Scanning Options

To specify which of these actions are performed on which objects, click the Set Scanning Options link in the Network Diagnostics window. You see the Network Diagnostics window shown in Figure 1. You have two ways to proceed:

• In the Actions section, activate the check box beside each action that you want Network Diagnostics to perform.

• In the Categories section, activate the check box beside each object that you want the actions performed on. (Note, however, that not all actions are performed on all objects. For example, the Connect action is performed only on the mail and news server and the Internet Explorer proxy server, if one exists on your network.)

Figure 1. Click the Set Scanning Options link to see the list of Network Diagnostics options.

When you’re done, click Save Options.

Running Network Diagnostics

To start the Network Diagnostics scan, click the Scan Your System link. Network Diagnostics displays the progress of the scan, as shown in Figure 2.

Figure 2. Network Diagnostics shows the progress of the scan.

When the scan has finished, you’ll see the results in a window similar to the one shown in Figure 3. Open the branches to see more detailed objects and the actions that Network Diagnostics performed on them. Look for FAILED in red type to see where possible problems occurred.

Figure 3. The results of a Network Diagnostics scan.

Running Network Diagnostics from the Command Line

You can also run network diagnostics during a Command Prompt session using the NETSH (Net Shell) utility.

For the ping action, you use the following command:

netsh diag ping object

Here, object is a parameter that specifies the object you want to ping. You can either specify an IP address or hostname, or you can use the built-in object names listed in Table 1.

Table 1. The object Parameter’s Built-in Names for the ping Action

Name	Pings
adapter	The network adapter
dhcp	The DHCP server
dns	The DNS server
gateway	The default gateway
ieproxy	The Internet Explorer proxy server
ip	The computer’s IP address
loopback	The loopback address (127.0.0.1)
mail	The default mail server defined by Outlook Express
news	The default news server defined by Outlook Express
wins	The WINS server

For example, the following command pings the default gateway:

netsh diag ping gateway

For the connect action, you use the following command:

netsh diag connect object

Here, object is a parameter that specifies the object you want to connect with. You can either specify an IP address or hostname, or you can use the built-in object names listed in Table 2.

Table 2. The object Parameter’s Built-in Names for the connect Action

Name	Connects With
ieproxy	The Internet Explorer proxy server
mail	The default mail server defined by Outlook Express
news	The default news server defined by Outlook Express

For example, the following command attempts to connect to the mail server:

netsh diag connect mail

For the show action, you use the following command:

netsh diag show object

Again, object is a parameter that specifies the object you want to display information about. You can use the built-in object names listed in Table 3.

Table 3. The object Parameter’s Built-in Names for the show Action

Name	Shows Information For
adapter	The network adapter
all	All the objects in this list
client	The installed network clients
computer	The computer
dhcp	The DHCP server
dns	The DNS server
gateway	The default gateway
ieproxy	The Internet Explorer proxy server
ip	The computer’s IP address
mail	The default mail server defined by Outlook Express
modem	All installed modems
news	The default news server defined by Outlook Express
os	The operating system
test	All the objects in this list; also performs all the actions in the Ping and Connect categories
version	The Windows and WMI (Windows Management Instrumentation) versions
wins	The WINS server

For example, the following command shows information for the network adapter:

netsh diag show adapter