HA prevents, DR restores, BC keeps the business operating.
These terms are related but not interchangeable. Mixing them produces bad architecture and confused incident response.
High availability
Reduce outage probability
- Replicas across zones
- Automated failover
- Normal component failure handling
Disaster recovery
Restore after major failure
- Backups and replication
- Runbooks and automation
- Region or platform recovery
Business continuity
Keep the company functioning
- People and vendors
- Status, support, and communications
- Regulatory and office continuity
Interview shortcut: HA handles common failure paths. DR handles exceptional failure paths. BC covers the whole operating business around both.