Given the following partial configuration for Router A:
interface serial 0
ip address 10.1.1.1 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint
router ospf 7
network 10.1.1.0 0.0.0.255 area 0
Which two statements are correct? (Choose two.)
A.
DR/BDR elections do not take place.
B.
The area 0 NBMA cloud is configured as more than one subnet.
C.
The router is restricted to a hub and spoke topology.
D.
OSPF neighbor statements are not necessary.
Explanation:
In an OSPF Point-to-Multipoint environment, DB/BDR elections do not take place.
The neighbor command became somewhat obsolete with the introduction of the capability to
configure other network modes for the interface, regardless of the underlying physical topology.Building Scalable Cisco Networks (Cisco Press) page 130 and 181
Point-to-Multipoint Network:
Point-to-multipoint is a single interface that connects to multiple destinations. The underlying
network treats the network as a series of point-to-point circuits. It replicates LSA packets for each
circuit. OSPF traffic is sent as multicast. There is no DR or BDR election. This technology uses
one IP subnet for all endpoints on the network.By default, the network is considered to be a series of point-to-point interfaces. There is no need
to specify neighbors, because the neighbors will see each other and simply become adjacent, with
no need for the election of a DR or a BDR. Point-to-multipoint does not try to reduce adjacencies
using a DR. Instead, it accepts the extra overhead of having a full set of adjacencies for the sake
of stability. Point-to-multipoint forms an adjacency automatically along any PVC, which causes
more overhead but is more resilient than NBMA.