Step-by-Step Comprehensive Detailed Explanation:
* Command Explanation:
* systemctl restart networkd restarts the network service to apply changes. The networkd service is responsible for managing network configurations in systems using systemd-networkd.
* Why Other Options are Incorrect:
* B: Enables the service to start on boot but does not apply immediate changes.
* C: Displays the status but does not apply changes.
* D: isolate changes the target (runlevel) and does not directly affect network configurations.
* References:
* CompTIA Linux+ Study Guide, Chapter on Networking Services
* man systemctl