Which of the following requirements is necessary to define a disaster recovery plan?

Sync/Async refers to replication methods (synchronous/asynchronous), which are techniques used within a DR plan, not the fundamental objectives themselves.

Recovery Point Objective (RPO) determines the maximum acceptable amount of data loss, while Recovery Time Objective (RTO) defines the maximum acceptable downtime after a disaster. These two metrics are crucial for designing a disaster recovery strategy, as they dictate the technologies and procedures required to meet business continuity needs.

HA (High Availability) and BC (Business Continuity) are broader concepts; BC is the overarching goal of DR, and HA is a strategy to achieve high uptime, but RPO/RTO are the specific measurable requirements that define the DR plan.

LAN/WAN refers to network types, which are infrastructure components but not the core requirements for defining a disaster recovery plan's objectives.