Which of the following is an example of a security token?

A security token is a physical or digital device that is used to gain access to a system or service, ensuring that the user is authentic and authorized. In this case, a physical token generating a random number for login is a prime example. These tokens often work by providing a one-time code that changes at regular intervals, adding a layer of security beyond just a username and password.

For instance, these physical tokens may be used in two-factor authentication systems, where the user must enter their password and then provide the code from the token for successful login. This mechanism helps prevent unauthorized access even if a password is compromised.

The other options, while related to cybersecurity, do not fit the definition of a security token. Password manager software assists users in securely storing and managing their passwords but does not generate a secure token for authentication purposes. A firewall application serves to protect networks by monitoring and controlling incoming and outgoing traffic based on predetermined security rules, while a network intrusion detection system is designed to identify and respond to malicious activities within the network. Neither of these options acts as a token to authenticate a user for access purposes.