Refer to the exhibit.
Exhibit 1

Exhibit 2

Exhibit 1 shows a simplified network topology. All infrastructure devices shown in the exhibit are
successfully implementing (OSPF) on the interfaces. The exhibit also shows settings for OSPF
areas. Exhibit 2 shows additional settings on IRF. The master within IRF 1 fails. Connectivity is
disrupted for about one minute.
What can the network administrator do to prevent this issue occurring again?

A.
Set up OSPF Bidirectional Forwarding Detection (BFD) on the routed link aggregation groups
between the IRF virtual switches

B.
Enable extended Link Access Control Detection Data Units (LACPDUs) on IRF 1 and IRF 4

C.
On IRF 1, set up Bidirectional Forwarding Detection (BFD) Multi-Access Detection (MAD) with a
dedicated link.

D.
On each of the IRF virtual switches, enable opaque LSAs and set the OSPF graceful restart
mode to IETF mode.

Explanation: