A project is having issues because people are making modifications to the servers without manager approval. This could have been avoided by using:

Change management is the process used to formally request, review, approve, implement, and verify all modifications to IT infrastructure, systems, or project scope. Implementing a robust change management process would require manager approval before any server modifications are made, thus preventing unauthorized changes.

An issues log documents problems that have already occurred, it does not prevent unauthorized changes proactively.

A communication plan ensures information flow, but it doesn't enforce approval processes for system modifications.

A risk register identifies potential future problems, but it doesn't implement controls for current system modifications.