JNCIA-Junos

A network engineer is designing an OSPF deployment and needs to ensure that on a multi-access broadcast segment, one router is elected to originate network LSAs on behalf of the segment while a second router stands ready to take over that function. Which pair of OSPF roles addresses this requirement?

An administrator wants to protect the switching network from a Layer 2 loop by preventing a port from transitioning if it unexpectedly receives BPDUs, and to prevent an inappropriate device from becoming the root bridge. Which two spanning-tree security features address these goals?