Resilience and recovery
Domain 3: Security Architecture · Not started
Main exam topics
Cloud and on-premises systems; virtualization, containers and industrial systems; shared responsibility; secure infrastructure and communications; segmentation and firewalls; protecting data at rest, in transit and in use; encryption, DLP, backups, redundancy and recovery.
SY0-701 topic overview · Independent study resource, not a prediction of exam questions.
Availability by design
High availability removes single points of failure using clustering, load balancing, redundant power, and multiple network paths. Load balancers spread traffic across servers and remove failed nodes. Geographic dispersal protects against regional disasters. UPS units bridge short outages, and generators cover longer ones.
Recovery objectives
The recovery time objective (RTO) is how long a service can be down before harm becomes unacceptable. The recovery point objective (RPO) is how much data loss, measured in time, is tolerable. An RPO of one hour means backups or replication must occur at least hourly. Mean time to repair (MTTR) measures how quickly failures are fixed, and mean time between failures (MTBF) measures reliability.
Backups and sites
Full backups copy everything. Incremental backups copy changes since the last backup of any kind, so restores need the full plus every incremental. Differential backups copy changes since the last full, so restores need the full plus the latest differential. Snapshots capture a point-in-time state. Keep at least one copy offline or immutable to survive ransomware. Hot sites are ready to run immediately, warm sites have hardware but need data, and cold sites provide only space and power.
Testing recovery
Untested backups are assumptions. Tabletop exercises walk through plans in discussion, failover tests move real workloads, and restore tests prove data can be recovered within the RTO.
Know the difference: Incremental vs. differential
| Aspect | Incremental | Differential |
|---|---|---|
| Copies changes since | Last backup of any type | Last full backup |
| Backup speed | Fastest | Slower over the week |
| Restore needs | Full + every incremental | Full + latest differential |
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