Explore usage of network connectivity tools: ipconfig, ping, tracert, pathping, and nslookup.
- [Instructor] Let's take some time to demonstrate how to use some of the common network connectivity tools. Let's drop onto our demo PC and take a look at how to use ipconfig. We can the CMD command or Powershell console for the command prompt window, click Start menu, then type in CMD and press Enter. Let's type ipconfig /all, which is one of the most popular commands, and we'll show a detailed report for all network interfaces. My other favorites require administrative level permissions and therefore we'll need to relaunch the command prompt.
I'll right click the icon, right click command prompt, and then select Run as Administrator, and select Yes. I can now run ipconfig /release and click Enter. This releases the IP configuration received from the DHCP server. If we type ipconfig /renew, this renews the DHCP configuration for all adapters that are set for auto configuration. And finally, the ipconfig /flushdns command is really useful if users are getting stale or out of date web pages, as this command will clear out the temporary DNS cache on the device.
There are several other parameters that can be used with the ipconfig command, which are reproduced here onscreen for your reference. Let's take a look at how to use ping. The ping command helps to verify IP level connectivity. When troubleshooting, you can use ping to send an ICMP echo request to a target host name or IP address. You'll use ping whenever you need to verify that a host computer can connect to the tcpip network, and network resources.
You can also use ping to isolate network hardware problems and incompatible configurations. First, I'll ping the loopback address to verify that tcpip is configured correctly on the local computer. The loopback address is a special address, and is 127.0.0.1. You can see from the results that the ping was successful. Actually, we could ping any address beginning with 127, since the whole of the 127 class A range was reserved for the loopback function.
Successfully pinging the loopback address confirms that our tcpip stack on our computer is fully functional. Now we'll ping the name of a device or network resource. We can see that when I try to ping LON-DC1, the ping request cannot find the host. This indicates there's a problem with the network. Perhaps LON-DC1 is not available, or that the router between the two machines is not functional.
In order to troubleshoot, we'd need to verify that the default gateway is functional, in the same way that we pinged a physical host, we can ping the gateway. We can see that the ping was successful, and that means that the default gateway is operational. Another useful feature of ping is where you're troubleshooting a fault. You can use the -t parameter and type ping -t and then the host address. The command will continue to run indefinitely, and this is great if you have an intermittent fault that you need to see.
Just imagine working in the cables or adding a new switch and seeing the connection resolve. To escape out of this command, we'll use Ctrl + C. These are some of the most common parameters that can be used with the ping command. I've reproduced them here on screen for your reference. Let's take a look at how to use trace route, which is a command line utility to trace the path that a packet takes to its destination. I'll type the command and then follow it by the host name or IP address of the destination machine I want to find.
Let's search for the web server hosting linkedin.com and push Enter. From the output the packet travels through various routers to get to the host, www.linkedin.com. And if there's a problem on the network, trace route will stop at the last router that it finds. Onscreen is a web reference for several options that you can use for the trace route, but in practice these are rarely used for standard troubleshooting.
Let's now take a look at how to use pathping, which is a command line utility that provides information about network latency and the network communications between a source and destination. I'll first clear the screen using cls. If we type pathping -n followed by the host name that I'm looking for, I'm looking for www.linkedin.com, and press Enter, we can see the first results list the path.
And by using the -n parameter, speeds up the process, as it does not attempt to resolve the IP addresses of all the routers. You can see the results are similar to when you use the trace route command. When you anlayze the results, you're looking for the routers or links that may show network problems, such as a slowness in responding or packet loss. We can see the trace is complete with no packet loss, except for the hop, number nine, which has resulted in 100 percent packet loss.
We'd therefore need to investigate this router for potential issues. These are some of the most common parameters that can be used with a pathping command. I've reproduced them here, onscreen, for your reference.
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