Hey it's Clint Garrett Ace Networker and we're gonna talk about how to ping a computer on a
network. How do we test connectivity from one computer or device to another computer
or device on that same network or even on another different network to find out that
they can pass data back and forth to each other, they can connect to each other. This
is where we come in with the Ping utility and we're going to talk about that, how it's used,
why network technicians admins anybody in networking is going to be using the ping
utility a whole lot. Stay tuned we're going to talk about that right now...
The Ping utility is used quite a bit in computer networking and in troubleshooting
network connectivity issues or when installing new components and hardware or computers onto
a network. The Ping utility is used to test the connection between 2 nodes on a network. So to
test a connection between these 2 nodes, you bring up a command-line interface. In Windows, it's
known as the CMD prompt window or command line prompt window. In this window you're going to type
in the word "ping" followed by the IP address or the host name of the other node you're trying to
ping. Now based on the output in your command-line interface window you can tell if the other node or
computer system is connected to the network and responding to that ping. Just a side note here:
The word ping was originally used in submarines when they would send out a sonar ping underwater
and see if those sound waves bounced off other submarines primarily or other objects under the
water. It literally made the sound like the word ping. The Ping utility in computer networking uses
the ICMP or Internet Control Message Protocol to send out an ICMP echo request to the other node,
the node that you're trying to ping. If the other machine or node can receive that test
packet and actually reply to it, it will and if and when it does you see a confirmation in your
command-line interface window as I mentioned a minute or two ago reporting success. Therefore,
the Ping utility can help a network admin or technician confirm that that other node is indeed
connected on the same network and can respond and IS responding. Now a number of things can be
deducted from a successful ping, chief among them are that all physical connections are working and
that there is nothing blocking the connection between the 2 nodes. One of the things I and
the other engineers I worked with would do quite frequently would be to try pinging that other node
and if it didn't respond we knew the IP address or the hostname of the switches or routers or other
nodes located between that intended node and the computer we were trying to ping it from, we would
try pinging those other devices in between to see if they responded back. By using the process of
elimination, we could sometimes tell where there was a disconnect or the connection was not working
like it needed to be. This would help us pin down the actual physical connection or components that
we needed to look more closely at to determine where the problem might exist. Now, that's moving
into more advanced networking and troubleshooting but I wanted to give you a small heads-up on
one of the main uses of the Ping utility. Now another use for the Ping utility is to test if
internet-based services are available. You can do this using FQDN or Fully Qualified Domain Names.
I'll talk more about FQDNS in another video but for now I'll just give you the basic description.
An example you can ping say www.google.com as a qualified domain name instead of the actual IP
address for Google (and they do use multiple IPs by the way). So a fully qualified domain name is
one that matches up to an IP address. Again, more on all of that later. The reason I bring up FQDNs
is because some sites will actually block ICMP echo requests to prevent users from using them for
testing. Sometimes a good test to use for actual internet connectivity from your network is to ping
a widely used websites from inside your network to see if those echo requests actually come back with
a response and that kind of proves to you that 'Yes' your internet connection is working. So then
you can troubleshoot looking at other things to see why certain websites aren't loading or people
aren't able to access certain things. You'll also find as you get more into security of networks,
especially corporate or enterprise level networks, that blocking ICMP echo requests from external
sites or hosts is another recommendation to prevent external hacking. So all of that being
said, and again I'll talk more about that in upcoming videos so you don't need understand
it all right now, let's just take a look at what a ping request looks like. I'm going
to bring up my command-line utility or CMD on my Windows operating system to first ping my
local home router's IP address. As you can see it responds back immediately because it's directly
connected to my computer. Now I'm going to ping www.google com and you'll see what the response
from their website is. So those are examples of successful pings, but what happens when the ping
cannot reach the other machine or when it cannot reach another machine that you're trying to ping?
You'll find the more you use Ping that there can be important clues that can help you with
troubleshooting connections or issues on a network found in the actual readout you get when the ping
doesn't go through. Now let me clarify here that the response you get may be different depending
on the operating system that you're using because different operating systems will give
you sometimes different readouts, but there are a couple of basic responses you get with ping when
the ping is not successful: 'unknown host' is one of those. If Ping is unable to turn a name into
an IP address, it's going to respond back with 'unknown host' This basically means "I don't know
the IP address of the domain name you tried to ping" In most cases this means you used an invalid
or unused DNS name. The other response you'll often get when Ping isn't able to complete to
the other host is 'destination host unreachable' This essentially means "I can't GET to that IP
address" This usually indicates a possible routing problem. Maybe the IP address or the FQDN you're
trying to ping is in a different network or subnet from the one the machine you're pinging from
is in and the ping request is not being routed correctly. If you're troubleshooting like I talked
about earlier, you might try pinging the default gateway IP address to see if it responds and etc.,
etc. And if a valid host just doesn't respond to a ping request, you'll often see something like
this. The more hands-on experience you get with computer networking the more you'll use the ping
utility to troubleshoot or confirm connections between two hosts on a network. This video is
just an introduction to the basics of Ping, as there are other options. You can use the
ping to get different helpful information but this is to give you a basic understanding of it
and hopefully to get you started down the path to your own career or business in networking.