A network planning diagram shows a large internetwork with many routers. The
configurations show that OSPF has been enabled on all interfaces, IP addresses correctly
configured, and OSPF workinG. For which of the following cases would you expect a router
to create and flood a Type 2 LSA?

A.
When OSPF is enabled on a LAN interface, and the router is the only router connected to
the subnet.

B.
When OSPF is enabled on a point-to-point serial link, and that router has both the higher
router ID and higher interface IP address on the link.

C.
When OSPF is enabled on a Frame Relay point-to-point subinterface, has the lower RID
and lower subinterface IP address, and otherwise uses default OSPF configuration on the
interface.

D.
When OSPF is enabled on a working LAN interface on a router, and the router has been
elected BDR.

E.
None of the other answers is correct.

Explanation:
OSPF creates a Type 2 LSA for a subnet when the router interface connected to the
subnet calls for the election of a designated router (DR), and at least two routers have
discovered each other and elected a DR. Then, the DR creates and floods the Type 2
LSA. IOS by default does not elect a DR on point-to-point topologies. It does on
router LAN interfaces. One answer states that one router only exists in the subnet, so
it does not actually find a second router and elect a DR. In the other case, a DR and
BDR have been elected, but the router described in the answer is the BDR, not the
DR. So, none of the other answers is correct.