The ping command is used when we want to test whether a connection to a
remote resource is possible. Usually this will be a website on the
internet, but it could also be for a computer on your home network if
you want to check if it's configured correctly. Ping works using the
ICMP protocol, which is one of the slightly less well-known TCP/IP
protocols that were mentioned earlier. The ICMP protocol works on the
Network layer of the OSI Model, and thus the Internet layer of the
TCP/IP model. The basic syntax for ping is ping <target>. In this example we are using ping to test whether a network connection to Google is possible:
Notice that the ping command actually returned the IP address for the Google server that it connected to, rather than the URL that was requested. This is a handy secondary application for ping, as it can be used to determine the IP address of the server hosting a website. One of the big advantages of ping is that it's pretty much ubiquitous to any network enabled device. All operating systems support it out of the box, and even most embedded devices can use ping!
The internet is made up of many, many different servers and end-points, all networked up to each other. This means that, in order to get to the content you actually want, you first need to go through a bunch of other servers. Traceroute allows you to see each of these connections -- it allows you to see every intermediate step between your computer and the resource that you requested. The basic syntax for traceroute on Linux is this: traceroute <destination>
By default, the Windows traceroute utility (tracert) operates using the same ICMP protocol that ping utilises, and the Unix equivalent operates over UDP. This can be altered with switches in both
instances.
You can see that it took 13 hops to get from my router (_gateway) to the Google server at 216.58.205.46
Pretty much whois <destination>
Might need to install on some systems.
When you visit a website in your web browser this all happens automatically, but we can also do it manually with a tool called dig . Like ping and traceroute, dig should be installed automatically on Linux systems.
Dig allows us to manually query recursive DNS servers of our choice for information about domains:dig <domain> @<dns-server-ip>