Which of the following is the default dead time of an interface on an OSPF...

The default Hello interval on an OSPF P2P (Point-to-Point) or Broadcast network is 10 seconds, and the default Dead interval is 40 seconds.

The Dead interval is the time a router waits without receiving a Hello packet from a neighbor before declaring it down.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“For broadcast and P2P network types, the default Hello interval is 10 seconds and the Dead interval is 40 seconds.”

(Chapter: OSPF Interface Types – Section: OSPF Timers)