What does the service password-encryption command do when entered into a router's configuration mode?

The service password-encryption command is used to enhance security within a router's configuration. When this command is executed while in configuration mode, it encrypts the passwords in the running configuration file, specifically any passwords defined in clear text. This means that even if someone gains unauthorized access to the running configuration, they will not be able to see the passwords in plain text; instead, the passwords will be displayed in an encrypted format.

By employing this command, network administrators ensure that sensitive authentication information remains protected from potential exposure, thereby improving the overall security posture of the networking device. This is particularly important in environments where configurations may be accessible to multiple users, including those who should not have direct access to sensitive information such as passwords.