Oddly enough this does not come up all that often but there has been times when I have needed the Windows native Telnet client to do some testing.  I have used it to see if a port is opened from a given client.  This is another simple how to.  

What is Needed:

1. Windows.
2. Possibly an internet connection.

The Fun:

With elevated permissions open a command prompt execute the following command:

dism /online /Enable-Feature /FeatureName:TelnetClient

This will install the native Telnet client.

Once this is installed it is simple to use. For example if I wanted to see if 443 was open on a given device.

telnet 10.2.3.4 443 

How you know that the port is open is when it does not fail like below:

Conclusion:

This is not a complicated one but it is still useful. Even though Putty and other SSH clients are out there and they can telnet. In my experience they have issues when what you are testing will not respond correctly to the telnet session. Even though I would not recommend using telnet to configure any device it still has its uses in todays world.