About the description of P2MP networking, which is correct? (Multiple Choice)

About the description of P2MP networking, which is correct? (Multiple Choice)
A . Devices with inconsistent mask lengths on the P2MP network cannot establish neighbor relationships. However, you can use the ospf p2mp-mask-ignore command to break this limitation.
B . The election of DR/BDR is required in the P2MP network.
C . No link layer protocol is P2MP by default. P2MP must be forcibly changed by other network types.
D . You can use the filter-Isa-out peer command to filter the sent LSA on a P2MP network

Answer: ACD