Which set of Cisco Internetwork Operating System (IOS) commands is used on Cisco routers to set a password for Telnet lines?

A.
router(config-router)# line vty 0 4
router(config-line)# login
router(config-line)# password password

B.
router(config)# line telnet 0 4
router(config-line)# login
router(config-line)# password password

C.
router(config)# line aux 0
router(config-line)# login
router(config-line)# password password

D.
router(config)# line vty 0 4
router(config-line)# login
router(config-line)# password password

Explanation:
The following commands are used on Cisco routers to set a password for Telnet lines:
router(config)# line vty 0 4
router(config-line)# login
router(config-line)# password password
An explanation of the commands is below:
router(config)# line vty 0 4: Enters line configuration mode for virtual terminal lines 0 to 4.
router(config-line)# login: Ensures that any remote access is prompted for a password.
router(config-line)# password password: Sets a password of “password” for VTY lines.
Assigning a password to the VTY lines is required for remote connections to the device to be possible. If a password has not been configured the following error
message will be generated when the connection is attempted:
Password required but not set
[Connection to foreign host 106.5.5.1 closed by foreign host]
Configuring a VTY password and requiring the password (accomplished with the login command) is good first step in securing Telnet access to the device. Another
step that can enhance the security of remote access to the device would be to apply an access list to the VTY lines with the access-class command.
The command sequence which begins with router(config-router)# line vty 0 4 is incorrect because the line vty 0 4 command should be executed in global
configuration mode, not routing protocol configuration mode.
The line telnet 0 4 command is incorrect because this is not a valid Cisco IOS command.
The line aux 0 command is incorrect because this allows you to configure the properties of the Auxiliary port, as opposed to the incoming Telnet (VTY) lines.
Objective:
Infrastructure Management
Sub-Objective:
Configure and verify device management

Cisco > Support > Technology Support > IP > IP Addressing Services > Design > Design TechNotes > Cisco Guide to Harden Cisco IOS Devices > Document ID:
13608
Cisco > Support > End-of-sale and End-of-life Products > Cisco IOS Software Releases 11.0 > Configuration Examples and TechNotes > Telnet, Console and AUX
Port Passwords on Cisco Routers Configuration Example