Routers R1 and R2, with router IDs 1.1.1.1 and 2.2.2.2, connect over an Ethernet WAN link. If using all default OSPF settings, if the WAN link initializes for both routers at the same time, which of the following answers are true? (Choose two answers.)
- Router R1 will become the DR.
- Router R1 will dynamically discover the existence of router R2.
- Router R2 will be neither the DR nor the BDR.
- Router R1’s show ip ospf neighbor command will list R2 with a state of “FULL/DR.”
Explanation: By default, IOS assigns Ethernet interfaces an OSPF network type of broadcast, with an OSPF interface priority of 1. As a result, both routers attempt to discover the other routers on the link (which identifies one correct answer).
The broadcast network type means that the routers also attempt to elect a DR and BDR. With a tie-in priority, the routers choose the DR based on the highest router ID (RID) values, meaning that R2 will become the DR and R1 will become the BDR.
These facts combine to show why the two incorrect answers are incorrect. The other correct answer is correct because the show ip ospf neighbor command lists the local router’s neighbor relationship state (FULL) and the role filled by that neighbor (DR), which would be the output shown on R1 when R2 is acting as DR.
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