It was a common trick for Windows admins to use telnet to test network port connectivity. Let me give you an example of what I am talking about. If you wanted to test to see if port 80 was open on a server you would type telnet host port. To test port 80 on this site you would type
telnet tunafreedolphin.com 80 and then you would either get timeout if it didn't connect which would indicate a failure or your session would connect to a blank window which would indicate that the port is open. I believe the telnet client was removed as part of default Windows install starting with Windows Vista. You can still install it under Windows Features but there is a better option.
PowerShell 3.0 and newer has a command called Test-NetConnection. If you are running Windows 7 Service Pack 1, Windows Server 2008 R2 SP1 and/or Windows Server 2008 Service Pack 2 then you may need to download a newer version of PowerShell from Microsoft. PowerShell 3.0 is included in Windows Management Framework 3.0.
Below are examples: