Identify Basic Internet Problems with ping

Identify Basic Internet Problems with ping
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Next time you call your help desk, do you want to wow them with your networking knowledge? Using a command called “ping”, built right into your existing Mac, Windows, or Linux computer, will help identify basic connection problems. Okay, this might not be enough to “wow” your fellow team members, however they will appreciate that you started the debug process. And please remember that your Support personnel are debug specialists, so follow their instructions when they step you through the troubleshooting sequence.

TL;DR:

You can use the ping command built into your Mac OS X, Windows, or Linux computer to identify basic network connectivity issues. This can help you solve the problem and/or gain valuable debug information as a first step before calling support. Read below for details on how to launch a command line window and run ping from your Mac OS X or Windows machine.

The ping command:

The ping command is a simple way to verify that another computer can receive information from you. The original author, Mike Muuss, actually named the program after the “ping” sound that a submarine sends to detect objects in the water. If an echo of the ping comes back, it means that there is something out there. In fact, ping uses the “Internet Control Message Protocol Echo Request” as part of its underlying software design.

In its simplest form, the ping command provides two valuable pieces of information, whether the message was echoed back (64 bytes from…) and how long it takes to receive the message back (e.g., time=6.396 ms). Depending on what type of computer you are using, you may even get a summary containing minimum, maximum, average, and more. The response time is shown in “ms”, or millisecond, which is 1/1000th of a second. A response time of 10ms or less is pretty fast, however values are often in the 100ms range. At much above 200ms you’ll probably notice that you have a sluggish connection.

When all is well:

This is what my ping response looks like on my Mac OS X computer when everything is working normally here in Malaysia:

MacBook-Pro:~ ajm$ ping Google.com
PING google.com (216.58.196.46): 56 data bytes
64 bytes from 216.58.196.46: icmp\_seq=0 ttl=55 time=6.396 ms
64 bytes from 216.58.196.46: icmp\_seq=1 ttl=55 time=6.368 ms
64 bytes from 216.58.196.46: icmp\_seq=2 ttl=55 time=26.773 ms
64 bytes from 216.58.196.46: icmp\_seq=3 ttl=55 time=6.984 ms
^C
--- google.com ping statistics ---
4 packets transmitted, 4 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 6.368/11.630/26.773/8.746 ms

This is what my ping response looks like on a Windows computer when everything is working well:

C:\Users\BJM>ping Google.com
Pinging google.com [216.58.196.46] with 32 bytes of data:
Reply from 216.58.196.46: bytes=32 time=6ms TTL=128
Reply from 216.58.196.46: bytes=32 time=15ms TTL=128
Reply from 216.58.196.46: bytes=32 time=6ms TTL=128
Reply from 216.58.196.46: bytes=32 time=6ms TTL=128
Ping statistics for 216.58.196.46:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 6ms, Maximum = 15ms, Average = 8ms

You can see from these examples that the connection is pretty good with average response times under 10ms.

When something is wrong (three examples):

So what would happen if I could not connect to Google.com? For example #1, I simulate a broken network connection to my Mac by unplugging my router from the wall, and re-run the command. The first thing I notice is that it takes a lot longer for the command to respond:

MacBook-Pro:~ ajm$ ping google.com
ping: cannot resolve google.com: Unknown host
MacBook-Pro:~ ajm$

Or, for example #2, depending on exactly how the connection is failing:

PING google.com (216.58.196.46): 56 data bytes
Request timeout for icmp\_seq 0
Request timeout for icmp\_seq 1
Request timeout for icmp\_seq 2
^C

And sometimes, if I have a particularly flaky connection, I’ll see a mixture of these messages. For example #3, I can simulate this by connecting my Mac computer to a public Wi-Fi connection that is across the street:

PING google.com (216.58.196.206): 56 data bytes
64 bytes from 216.58.196.206: icmp\_seq=0 ttl=57 time=273.655 ms
64 bytes from 216.58.196.206: icmp\_seq=1 ttl=57 time=808.546 ms
64 bytes from 216.58.196.206: icmp\_seq=2 ttl=57 time=179.613 ms
Request timeout for icmp\_seq 3
Request timeout for icmp\_seq 4
64 bytes from 216.58.196.206: icmp\_seq=5 ttl=57 time=374.612 ms
Request timeout for icmp\_seq 6
ping: sendto: No route to host
Request timeout for icmp\_seq 7
ping: sendto: No route to host
Request timeout for icmp\_seq 8
^C

In the first test, ping told me that my machine could not even find the Internet address (IP 216.58.196.46) for Google.com. In the second test, my computer remembered Google’s IP address, but could not actually reach the Google servers (Request timeout). In the third test, sendto: No route to host means that the network device knows where the Google servers are, but something along the digital pathway is broken.

Mac Users: How to run the ping command:

On a Mac, you typically run ping from the terminal command line. To start the terminal, click the OS X Spotlight magnifying glass icon in the upper right of the desktop:

Mac Spotlight

When the search window appears, type “terminal”, highlight “Terminal – Utilities”, and double-click (or hit

return

):

That will launch the terminal command window, and you can enter the command ping Google.com shown in my examples:

Important Mac Tip : The ping command will run forever if you don’t tell it to stop. To do that, press the

control

key (lower right on keyboard) and the

c

key. That will interrupt the test with a Control-C (^C) and give back command line control. For Windows user, the command will stop by itself after a few iterations.

Windows Users: How to run the ping command:

Opening the Command Prompt differs between Windows versions 10, 8.1, 8, and 7; here’s a great guide at How To Open Command Prompt. On a Windows 7 machine, for example, click on the lower left Windows “Start” icon, and select “Command Prompt” and double-click (or hit

enter

):

Win Terminal Launch

This will launch the command window, and you can enter the command ping Google.com shown in the examples:

Now that you know how to use the ping command, you can do basic troubleshooting of your network connection. With a little bit of creativity, you can work with your local IT support person or knowledge of your network topology and IP address (e.g., ping the router, ping your ISP) to further identify network issues.