Useful Basic Network Troubleshooting Commands

My previous posts were about things that required a pretty thorough understanding of specific technologies.  I mean they were hard.  So here’s an easier one.  This post contains instructions on how to use basic network troubleshooting commands to narrow down the reason behind why the Internet isn’t working on your computer the day you really need it to get that stuff done.

Difficulty:    Level 1

  1. Open the Start Menu
  2. Go to All Programs (or Programs, depending on your Windows configuration)
  3. Go to Accessories
  4. Under Accessories, click Command Prompt
  5. This window opens:blankcmd
  6. Type ipconfig and press enter
  7. A list of information will appear, you’re looking for IP Address (or IPv4 address if you’re using Vista) and Default Gateway.
  8. To make things a little more clear, I’ll pretend my IP address is 192.168.0.101 and my default gateway is 192.168.0.1.  Your address and gateway will probably be different but both will be in the form of X.X.X.X where X is a number.
  9. You just learned the ipconfig command, which tells you some basic information about your computer’s network card’s configuration.
  10. In the command prompt type ping followed by your default gateway, so for me the full command would be ping 192.168.0.1
  11. Press enter.  You should get four Reply messages.  If you get a message that doesn’t say “Reply from …” then either there’s a problem with your computer’s network card or the default gateway (which is actually your router or modem).  If you do an ipconfig and see your computer still has an IP address, it’s likely a problem with your gateway.
  12. Now ping an address on the Internet, such as www.technicallyamusing.com.  You should get 4 replies.  If you don’t get replies but you could ping your default gateway, there’s something wrong between the gateway (usually your cable or DSL modem) and the connection to the ISP.  Your computer’s settings are likely fine.
  13. If you don’t get any replies from the Internet address, try pinging 4.2.2.1, if you get replies from that but not from pinging a domain name (like technicallyamusing.com), you have a DNS configuration problem.  You’ll probably need to contact someone who can help you correct that as it’s beyond the scope of this post.
  14. Okay, now type tracert www.technicallyamusing.com and hit enter
  15. Tracert (short for traceroute) shows you the entire path your data takes when going to a specific destination.  Let it run for a little bit and watch it display the “hops” as it goes.  Each hop represents a new network, each network in turn passes the data on to another network until the data gets to where it’s supposed to go.  The tracert command just displays each hop to you.  The path the data takes and any hop on that path may change each time data is sent due to the way networks work.  It’s kind of cool to see it in action though.
  16. If when you’re running the tracert command you notice that everything after a certain hop is all asterisks, then the first hop that’s an asterisk is a network that is having a problem forwarding your data on for some reason.

So to sum up, the commands covered were ipconfig, ping, and tracert.  These are very useful commands and can be used in much more powerful ways than demonstrated above.  For any command prompt …command… you can look at the various options the command offers by typing /? after the command.

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