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        | An interface that enables the user to interact with the operating system by entering commands and optional arguments. |  | 
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        | A TCP/IP application layer protocol that supports terminal emulation between a client and server, using dynamic key exchange and encryption to keep the communications private. |  | 
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        | A part of the Cisco IOS CLI in which the user can use the most powerful and potentially disruptive commands on a router or switch, including the ability to then reach configuration mode and reconfigure the router. |  | 
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        | A mode of the user interface to a router or switch in which the user can type only nondisruptive EXEC commands, generally just to look at the current status, but not to change any operational settings. |  | 
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        | A part of the Cisco IOS Software CLI in which the user can type configuration commands that are then added to the device’s currently used configuration file (running-config). |  | 
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        | In Cisco IOS switches and routers, the name of the file that resides in NVRAM memory, holding the device’s configuration that will be loaded into RAM as the running-config file when the device is next reloaded or powered on. |  | 
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        | In Cisco IOS switches and routers, the name of the file that resides in RAM memory, holding the device’s currently used configuration. |  | 
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        | The standard terminal-emulation application layer protocol in the TCP/IP protocol stack. Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system. Telnet is defined in RFC 854. |  | 
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        | Term 
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        | Internetwork Operating System |  | 
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        | Term 
 
        | Internetwork Operating System |  | Definition 
 
        | Cisco operating system software that provides the majority of a router’s or switch’s features, with the hardware providing the remaining features. |  | 
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        | Cisco switches refer to the console as the console line – specifically console line 0. |  | 
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        | Switches support 16 concurrent Telnet sessions which are called virtual terminal (vty) line. The term vty  refers to the old name for terminal emulators. This includes Telnet and SSH access. |  | 
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