Network Diagnostics in Windows Vista

Network Diagnostic Tools in Windows Vista

In the Network Sharing Center there is a Diagnose and Repair link that will scan your system for network issues. This diagnostic pings the remote host. If it is not found, you have the option to reset the network adapter Local Area Connection.

In addition to the automated Network Diagnostics interface, several tools are included with Windows Vista that can be used to test network components and connectivity.

Basic Tools

The following tools are fundamental in connectivity and name resolution troubleshooting. In addition, they are useful when troubleshooting failures with applications that communicate on the network or Internet.


The Ipconfig command line tool displays all current TCP/IP network configuration values. Used without parameters, the ipconfig command displays the IP address, subnet mask, and default gateway for all adapters. In addition, you can use the following commands:

ipconfig /all – If you want to see more detailed information on the configuration for all interfaces on the computer, use this command.

ipconfig /release – This command releases any DHCP addresses assigned to interfaces on the computer. You can typically use it before the next command.

ipconfig /renew – This command causes the DHCP client service to request network addresses for all network connections. It is useful when you encounter connectivity problems and suspect a bad address. It is also used when troubleshooting name resolution failures to ensure the interface has the correct DNS server addresses assigned.

ipconfig /flushdns – This command clears the local DNS resolver cache. When you connect to machines by name, the DNS client software on the computer stores names and IP addresses as they are resolved. This is so that the name can be resolved without sending a repeat request to the DNS server. If a remote computer’s IP address changes, outdated information in this cache can cause connections by name to fail. Run this command on the local machine to clear the cache.


The ping command verifies IP-level connectivity to another TCP/IP computer by sending ICMP Echo Request messages. The receipt of corresponding Echo Reply messages is displayed along with round-trip times.

Ping is the primary TCP/IP command used to troubleshoot connectivity, reachability, and name resolution.

Because firewalls typically block ICMP traffic, ping does not receive a response from a system with a firewall configured. Check the firewall settings to ensure Ping or ICMP Echo is enabled while you are troubleshooting.


The Trace Route (Tracert.exe) command determines the path taken to a destination by sending ICMP Echo Request messages to the destination with incrementally increasing Time to Live (TTL) field values. The path displayed is the list of near-side router interfaces of the routers in the path between a source host and a destination. The near-side interface is the interface of the router closest to the sending host in the path.

This command is useful for troubleshooting connectivity failures when you can ping the default gateway but cannot ping Internet servers. Such a situation can indicate a failure in the routing from the client machine to the Internet.

Running Tracert returns data on the failure indicating which hop in the routing is dropping the traffic. When used for Internet connectivity troubleshooting, the data gathered is often used to work with the ISP to resolve such routing issues. The output should identify the router at which the problem occurs.

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