OSPF is configured over a Frame Relay network as shown in the exhibit. All PVCs are
active. However, R1 and R3 fail to see all OSPF routes in their routing tables. The show ip
ospf neighbor command executed on R2 shows the state of the neighbors. What should be
done to fix the problem? Select the best response.

A.
The ip ospf network non-broadcast command should beconfigured on each Frame
Relay interface.

B.
The ip ospf network broadcast command should be configured on each Frame Relay
interface.

C.
The neighbor command should be configured under theOSPF routing process on all
routers.

D.
The ip ospf priority value on the hub router shouldbe set to 0.

E.
The ip ospf priority value on the spoke routers should be set to 0.

Explanation:
In an NBMA network topology, neighbors are not discovered automatically. OSPF tries to
elect a DR and a BDR due to the multi-access natureof the network, but the election fails
since neighbors are not discovered because NBMA environment doesn’t forward broadcast
and multicast packets. Neighbors must be configuredmanually to overcome these
problems.
Also, additional configuration is necessary in a hub and spoke topology to make sure that
the hub routers, which have connectivity with everyother spoke router, are elected as the
DR and BDR. You must set the spoke interfaces to anOSPF priority of zero, this ensures
that the spokes will not become the DR or BDR.