Most meeting or conferencing applications default to the built-in laptop camera unless manually changed.
When an external camera is connected, the software may continue to use the default device, resulting in a blank preview, especially if the internal camera is disabled, covered, or malfunctioning. CompTIA A+ stresses verifying correct device selection when peripherals are installed.
Selecting the correct camera source is a quick, non-invasive test that resolves the issue in the majority of cases. The technician should open the application's video settings and choose the external webcam from the camera dropdown menu.
Replacing the camera (B) is premature without confirming configuration. Updating software (C) is beneficial but will not resolve a simple input-selection error. Checking the cable (D) is a valid step if the preview still fails after selecting the device.
Thus, the correct next step is to select the proper camera source.