| 4.2 |  | Getting Information about Remote Devices |
| 4.2.1 |  | Telnet |

| Telnet is a virtual terminal protocol that is part of the TCP/IP protocol suite. It allows connections to be made to remote hosts. Telnet provides a network terminal or remote login capability. Telnet is an IOS EXEC command used to verify the application layer software between source and destination. This is the most complete test mechanism available. Telnet functions at the application layer of the OSI model. Telnet depends on TCP to guarantee the correct and orderly delivery of data between the client and server. A router can have multiple simultaneous incoming Telnet sessions. The range zero through four is used to specify five VTY or Telnet lines. These five incoming Telnet sessions could take place at one time. It should be noted that verifying application layer connectivity is a byproduct of Telnet. The main use of Telnet is remote connection to network devices. Telnet is a simple and universal application program.