Which metric relates to the requirement that data at the disaster recovery site must not be more than 24 hours old?

The metric that specifically pertains to the requirement that data at the disaster recovery site must not be more than 24 hours old is the Recovery Point Objective (RPO). RPO defines the maximum age of data that an organization is willing to lose in the event of a disaster. A 24-hour RPO indicates that if a disaster were to occur, the organization will only be able to restore data that is no older than 24 hours. This means that any data created or modified in the last 24 hours may be lost depending on the backup and replication processes in place.

Understanding RPO is crucial for organizations as they formulate their disaster recovery strategies. It helps them determine how frequently they need to back up their data and how quickly they must be able to replicate it to ensure minimal data loss. Thus, having an RPO of 24 hours implies that backups or replication processes should occur at least once every 24 hours to comply with that requirement.