Routers R1, R2, R3, and R4 connect to the same 10.10.10.0/24 LAN-based subnet.
OSPF is fully working in the subnet. Later, R5, whose OSPF priority is higher than the other
four routers, joins the subnet. Which of the following are true about the OSPF database
exchange process over this subnet at this point? (Choose two.)

A.
R5 will send its DD, LSR, and LSU packets to the 224.0.0.5 all-DR-routers multicast
address.

B.
R5 will send its DD, LSR, and LSU packets to the 224.0.0.6 all-DR-routers multicast
address.

C.
The DR will inform R5 about LSAs by sending its DD, LSR, and LSU packets to the
224.0.0.6 all-SPF-routers multicast address.

D.
The DR will inform R5 about LSAs by sending its DD, LSR, and LSU packets to the
224.0.0.5 all-SPF-routers multicast address.

Explanation:
Because the subnet was stable before R5 arrived, the other routers will have
elected a DR and BDR. OSPF does not preemptively elect a new DR nor BDR, so R5
will be neither (DROther). As a result, R5’s messages to the DR will be sent to the
224.0.0.6 all-DR-routers multicast address, and the DR’s messages directed to R5 will
be sent to the 224.0.0.5 all-SPF-router address.