Test 2: Testing Basic Local Connectivity

Test 2: Testing Basic Local Connectivity with ping and ipconfig

In this part, we run a simple test, called the localhost ping test, to make sure that the computer can talk to itself properly. That may sound strange, but the localhost IP is used by the operating system for many things. It is also a further step in making sure that things are going right, and it's simple to perform. If this test works, it doesn't guarantee that your network is set up correctly, but it if fails, it almost guarantees that this computer won't communicate with any network.

First, we need to open a Command Prompt window. To do this, select All Programs from the Start menu, then Accessories and finally Command Prompt as shown below. (Windows Vista and XP use the name "All Programs" as the name in its standard Start menu; Windows 2000 just uses the name Programs.)

Opening a Command Prompt window

This will bring up a Command Prompt window similar to the one shown below. In the Command Prompt window, type in the ipconfig command at the prompt and hit return. (Don't worry if your prompt is different than C:\>. I have done a cd \ command before starting this part.)

ipconfig in a Command Prompt window

What we are looking for here is another confirmation that the Ethernet adapter is present and recognized. For now, don't worry about any of the numbers; just look to see that you have an adapter listed. (Note: You may have to connect a cable between your Ethernet adapter and a port on your [router or] switch so that a valid link is established. Some Ethernet adapters seem to require this before they will be recognized as being present.)

Next, type in the command ping 127.0.0.1. The IP address 127.0.0.1 is reserved as the "localhost" or "loopback" address for every device to refer to itself. It's always a valid address for the machine. Typing ping localhost will result in the same reply responses. Later, we'll be assigning an IP address (or having one assigned to us), but the localhost name is always available. If everything is set up properly, you will see replies from the ping command like the ones shown below. Technically, you should always be able to ping 127.0.0.1 even if there is no Ethernet adapter installed in your computer so long as the basic networking software has been installed. The localhost ping just verifies that.

Localhost ping response

If you aren't getting this, you should recheck that your Ethernet adapter and the drivers it requires are installed (and that you've installed the proper drivers for the operating system you are using). I've never had this fail if with an Ethernet adapter that's correctly installed.

If you typed ipconfig and got something like the following response, check to make sure your network card is still properly inserted. You should also redo test number 1.

Ethernet adapter not found

The ipconfig and localhost ping tests are very simple and quick checks to make sure basic networking functionality is there. Whenever you have a network problem, these are the first things you should try. The ipconfig command has some useful options that we'll get into later, but for now, commit these basic commands to memory.

Back in the days before built-in Ethernet ports where common in laptops, I occasionally forgot to insert my laptop card. The above response is what I got in that case. Also, I've seen cases where the Ethernet cable was jerked on hard enough (e.g., stepped on or tripped over) to pull the Ethernet adapter partially out of the PCI slot in a desktop machine. If you suddenly start getting the above response on a desktop machine that's been working fine "forever," either the card has become unseated from the PCI slot or it has just plain died. I've had both happen. (Check the cable as well.) If you get the above response from a new Ethernet adapter, usually it means the drivers installed weren't the right ones or failed to load for some reason. Although rare, I have had a brand new Ethernet adapter fail right out of the box.