Which of the following is a network diagnostic tool that monitors and records network information?

A protocol analyzer is a network diagnostic tool that captures and analyzes data packets as they travel across a network. It provides insights into network traffic, including protocols in use, performance metrics, and potential issues such as bottlenecks or security vulnerabilities. By monitoring and recording network information in real time, it helps network administrators troubleshoot problems, optimize performance, and ensure the integrity of network communications.

The other options do not serve the same purpose. An online monitor may refer to general monitoring of systems or services but lacks the specific diagnostic capabilities of a protocol analyzer. A downtime report typically focuses on summarizing periods when systems were unavailable, rather than analyzing live network data. A help desk report may track user issues or support tickets but does not provide detailed network traffic analysis. Thus, the protocol analyzer is the distinct choice among these options for monitoring and recording network information.