Refer to the exhibit.

IRF 3 and Switches 1, 2 and 4 are successfully implementing OSPF on the interfaces shown in the exhibit.
Then IRF 3’s 10.1.10/24 link fails. Connectivity between Server 1 and Server 2 is disrupted for about 30
seconds.
What can the network administrator do to prevent this issue from occurring again?

A.
Enable opaque LSAs on each of the switches; set the OSPF graceful restart mode to IETF mode on at least
IRF 3.

B.
Set the OSPF dead timer on each of the switches to equal the hello timer

C.
Set up OSPF Bidirectional Forwarding Detection (BFD) on each switch VLAN 10 interface.

D.
On IRF 3, set up Bidirectional Forwarding Detection (BFD) Multi-Active Detection (MAD) on a dedicated link
between the members.

Explanation:
In a nutshell, the OSPF enhancements for graceful restart are as follows:
– The router attempting a graceful restart originates link-local Opaque-LSAs, herein called Grace-LSAs,
announcing its intention to perform a graceful restart within a specified amount of time or “grace period”.
– During the grace period, its neighbors continue to announce the restarting router in their LSAs as if it were
fully adjacent (i.e., OSPF neighbor state Full), but only if the network topology remains static (i.e., the contents
of the LSAs in the link-state database having LS types 1-5,7 remain unchanged and periodic refreshes are
allowed).
https://tools.ietf.org/html/rfc3623