You get a scenario question on the SY0-701. A company's database can lose at most 15 minutes of transactions, and it has to be back online within 2 hours of an outage. The question asks which metric describes the 15 minutes. If you have to stop and think, you are not alone. The recovery and risk metrics are some of the easiest points on the exam to bank and some of the easiest to throw away, because four of them sound almost identical and the test writers know it.
Here is how I finally got them to stick.
The two recovery metrics: RTO and RPO
Both are about time, but they measure different things. The trick is to anchor each one to the moment of the outage.
RPO, recovery point objective, looks backward from the outage. It answers "how much data can we afford to lose?" If your RPO is 15 minutes, your backups or replication have to be recent enough that you never lose more than 15 minutes of work. RPO drives how often you back up.
