When troubleshooting the issue, you notice the election of a new root bridge with an unknown
MAC address. Knowing that all access ports have the PortFast feature enabled, what would be the
easiest way to resolve the issue without losing redundant links?

A.
Enable bpduguard globally.

B.
Enable rootguard.

C.
Enable loopguard.

D.
Enable spanning tree.

E.
Enable UDLD.

Explanation:
Loopguard, spanning tree, and UDLD are obvious red herrings. This leaves enabling rootguard or
bpduguard. One key is that enabling bpduguard only affects ports that have portfast enabled; see
the following URL under “Configuration.”