What is a primary feature of Vault's audit logging?

A primary feature of Vault's audit logging is its capability to provide comprehensive logs that include all access and modifications. This means that every action taken within Vault, whether it's a successful data read, write, or deletion, is recorded. The audit logs serve as an essential tool for security and compliance, allowing administrators to have a clear and detailed record of how sensitive data is accessed, modified, or deleted, who performed these actions, and when they occurred. This granular level of detail enables organizations to track user activity and ensure accountability, which is crucial for security audits and incident response.

The other options do not fully capture the scope and intent of Vault's audit logging. Logging only user authentication attempts would not provide a complete view of actions occurring within the Vault environment. Exclusively logging API errors would also miss out on tracking successful operations, thus failing to provide a comprehensive audit trail. Monitoring network traffic would fall outside the purview of Vault’s audit logging and would not contribute to understanding user actions or access patterns within Vault itself. Therefore, the choice providing logs that include all access and modifications is the most accurate representation of Vault's audit logging capability.