What command is used to configure a router as a Designated Router (DR)?

The command used to configure a router as a Designated Router (DR) is indeed "ip ospf priority [value]." This command sets the OSPF priority of the router interface, which is the key factor in determining which router becomes the DR in a broadcast network. In OSPF, when a new neighbor adjacency is formed, each router compares its OSPF priority to elect the DR and Backup Designated Router (BDR). The router with the highest priority value becomes the DR. If two routers have the same priority, the router with the highest Router ID is selected as the DR.

The other options do not correctly reflect the command syntax used in OSPF configuration. Therefore, the choice presented accurately captures the necessary configuration step to influence DR election in OSPF environments. Understanding the importance of OSPF priority can greatly aid in managing network traffic and ensuring efficient routing.