Which action must be taken to avoid this attack and still be able to advertise this subnet into OSPF?

Refer to the exhibit.

An attacker can advertise OSPF fake routes from 172.16.20.0 network to the OSPF domain and black hole traffic .

Which action must be taken to avoid this attack and still be able to advertise this subnet into OSPF?
A . Configure 172.16.20.0 as a stub network.
B . Apply a policy to filter OSPF packets on R2.
C . Configure a passive Interface on R2 toward 172.16.20.0.
D . Configure graceful restart on the 172.16.20.0 interface.

View Answer

Answer: C