Network Troubleshooting Video Series


Episode 20, Segment 06 of 06

After that, try pinging some well-known computer out on the worldwide Internet. For our purposes in this movie, we are going to select "" the main gateway router leading to the campus network at the Massachusetts Institute of Technology. Let's illustrate that router right here.

(click on small image below to see enlarged version)

As shown in this illustration from inside the Internet, we can access this router through a series of other routers leading from our own Internet Service Provider.

Accordingly, when we use the the - "ping" - utility from inside our own computer on our own network, a series of brief messages are addressed to and are transmitted, through our own NAT router and cable or DSL modem, through our own ISP, through the Internet to MIT. Upon receipt, MIT's main router constructs a response message and sends it back to us. The most popular ping utilities send four separate messages at one second intervals.

(Because these messages are assigned a low priority on the Internet, we might expect a slight delay receiving one or more of the response messages. If the router at MIT or any of the intervening routers is saturated with higher-priority traffic, one or more of the queries or responses might become entirely lost. An occasional lost ping packet should be interpreted as an indication of a network node that is very busy, but it does not indicate any kind of a serious failure.)

With experience, you'll become very comfortable using - "ping" - to verify proper connection of your Internetworked computers and other equipment. You should always be able to ping your own computer and all of the other computers on your own network. Whenever your Internet Service Provider is giving you proper service, you should also always be able to ping other well-known locations on the worldwide Internet. Take advantage of the information found here and in other movies at to identify problem areas and to keep your network running at its best!

Episode 21, Segment 01 of  01