Use TRACERT to Troubleshoot TCP/IP Problems in Windows
How to Use the TRACERT Utility
Traceroute is a command which can show you the path a packet of information takes from your computer to one you specify. It will list all the routers it passes through until it reaches its destination, or fails to and is discarded. In addition to this, it will tell you how long each 'hop' from router to router takes.
In Windows, select Start > Programs > Accessories > Command Prompt.
Crtl +R > Type CMD and hit enter
In command Prompt Enter the word tracert, followed by a space, then the domain name.
Firstly it tells you that it's tracing the route to yourdoamin.com, tells you the IP address of that domain, and what the maximum number of hops will be before it times out.
This is extremely useful when trying to find out why a website is unreachable, as you will be able to see where the connection fails. If you have a website hosted somewhere, it would be a good idea to do a traceroute to it when it is working, so that when it fails, you can do another traceroute to it (which will probably time out if the website is unreachable) and compare them. Be aware though, that it will probably take a different route each time, but the networks it passes through will generally be very similar.
It is generally recommended that if you have a website that is unreachable, you should use both the traceroute and ping commands before you contact your ISP to complain. More often that not, there will be nothing to your ISP or hosting company can do about it.