Cisco Certified Network Associate (CCNA) Practice Exam

What command would a network administrator use to allow only one Telnet connection and encrypt the password?

1. (config)#service password-encryption

2. (config)#line vty 0

3. (config)#username USERNAME password PASSWORD

4. (config-line)#login

The correct answer is: (config)#service password-encryption

The correct command to allow only one Telnet connection and ensure that the password is encrypted is related to the service password-encryption command. When this command is configured, it encrypts all plaintext passwords in the configuration file, thereby enhancing the security of the passwords used for accessing the device, including those for Telnet sessions. While the service password-encryption command secures passwords, managing Telnet connections is also critical. It is worth noting that to limit the number of concurrent Telnet connections, the network administrator would typically need to configure the terminal lines directly under-line vty settings and set appropriate limits. However, the command that directly contributes to password encryption—enhancing overall security—is indeed the service password-encryption command. In this context, while options related to line configuration or user authentication are relevant to session management, they do not specifically pertain to encrypting passwords alone, nor do they focus solely on limiting Telnet connections. The intention of the question is geared towards encryption, making the first command the most appropriate choice.