Which of the following steps of the troubleshooting methodology should a technician take to confirm...

To confirm a theory in the troubleshooting process, the technician should duplicate (replicate) the problem under controlled conditions. In the Network+ (N10-009) methodology, confirming a theory means validating that the suspected cause actually produces the observed symptoms. Replicating the issue helps ensure the technician is not chasing a coincidence, and it allows changes to be tested safely (for example, reproducing the issue with a specific user account, endpoint, cable, port, SSID, or configuration). If the problem can be duplicated, the technician can then try targeted actions to see whether the symptoms change in predictable ways—strengthening or disproving the hypothesis.

The other choices occur earlier as part of forming the theory. Identify the symptoms is an initial step to define the problem clearly. Gather information is part of the discovery phase—collect logs, error messages, topology details, and user observations. Determine any changes is also an early step used to correlate recent modifications (patches, new devices, config changes) with the onset of the issue. Those steps help create a theory; duplication helps confirm it before implementing a full fix.

===========