What is a characteristic of a PAM module marked as "sufficient"?

When a PAM (Pluggable Authentication Module) module is marked as "sufficient," it signifies that if this module successfully completes its authentication task, the application processing the authentication will immediately consider the entire authentication process a success, without needing to evaluate any subsequent modules. This characteristic allows for efficient handling of authentication, especially in scenarios where a user's credentials may pass one of the authentication checks and it is unnecessary to check further.

This functionality is beneficial because it can lead to reduced overhead in authentication processes, enhancing system performance. If a "sufficient" module fails, the outcome is determined by any previously evaluated modules or any remaining modules that may be required to complete the authentication sequence. This is in stark contrast to modules that are marked as "required," which must succeed for the overall authentication to succeed, regardless of any subsequent module results.