When configuring Prism Central, two log modules that are capable of forwarding messages to an external syslog server are API Audit and Flow. The API Audit module tracks and logs API requests, which is crucial for maintaining a detailed record of interactions with the system. The Flow module logs network activity and security-related events, which can be critical for monitoring and analyzing network traffic and security incidents. These functionalities align with the need to have logs that can be externally analyzed for audit and security purposes.