Troubleshooting Transport Layer Issues on Network Hosts
Gathering transport layer information on Windows machines

Telnet
The usefulness of Telnet in troubleshooting comes from its ability to connect to a specific destination port on a remote server, allowing it to be used to confirm correct traffic flow from a client to remote server. Telnet is particularly useful for transport layer diagnostics.

Telnet can be run as either a command line utility or with a GUI. Figure shows the command line Telnet application being used to confirm connectivity to a POP3 server.

ipconfig Command
The ipconfig /all command can provide the network engineer with a lot of information about the configuration of a Windows-based machine. This information covers details from the MAC address at Layer 2, the IP address at Layer 3, NetBIOS information at Layers 4 and 5, to DNS information at Layers 6 and 7.