A serial interface between R1 and R2 uses PPP and OSPF in a single area. By default, what OSPF network type is shown by show ip ospf interface?

When OSPF is configured over a serial interface using PPP encapsulation, the OSPF network type defaults to point-to-point. This is because PPP is inherently a point-to-point protocol, establishing a direct connection between two devices. In a point-to-point OSPF network, there is no need for a Designated Router (DR) or Backup Designated Router (BDR) as there are only two routers in the segment, and they can directly exchange routing information. Nonbroadcast is incorrect because it's typically used for Frame Relay or ATM interfaces where broadcast is not supported, and neighbors must be manually configured. Point-to-multipoint is incorrect as it's used for hub-and-spoke topologies over nonbroadcast media. Broadcast is incorrect because it's the default for Ethernet interfaces where multiple devices can share the same segment and broadcast traffic is supported.