Implementing Cisco IP Switched Networks (SWITCH v2-0) (#448)

A network engineer deployed an older switch with the same spanning-tree priority as the existing root, which caused a network outage. In which two locations should the Spanning Tree protocol root guard feature be implemented? (Choose two.)

On the designated root switch downlinks to the access layer.
On all of non-root switch facing ports of the access layer
On the access layers root facing ports
On Layer 3 boundaries in the distribution layer
Globally on all network switches.