Describe high availability and disaster recovery strategies

1. The business can lose at most 15 minutes of data. Which objective is that?

C. RPO is the maximum acceptable data loss, measured in time.

2. The business needs the system back within 1 hour after an outage. Which objective is that?

B. RTO is the maximum acceptable time to restore service.

3. What's the main difference between high availability and disaster recovery?

A. HA handles node or zone failures with little or no downtime; DR covers regional disasters with RPO/RTO targets.

4. A 99.95% SLA for a single service allows roughly how much downtime per month?

A. 0.05% of ~43,800 minutes is ~22 minutes.

5. Two services in series have SLAs of 99.95% and 99.99%. What's the composite SLA?

A. Multiply: 0.9995 × 0.9999 ≈ 0.9994. Every dependency lowers the composite SLA.

6. VMs must survive the failure of an entire datacenter within a region. What do you use?

C. Zones are physically separate datacenters in a region. Availability sets only protect against rack and update failures.

7. What does an availability set protect against?

B. Availability sets spread VMs over fault and update domains in one datacenter.

8. Which service replicates Azure VMs to another region and orchestrates failover?

B. Site Recovery is the DR service: continuous replication plus recovery plans for failover.

9. Which built-in HA does Azure SQL Database provide without any configuration?

A. The service handles local HA itself. Zone redundancy and geo-replication are options you enable.

10. An Azure SQL Database must fail over to another region with a single endpoint that apps don't have to change. What do you configure?

B. Failover groups provide listener endpoints that follow the primary. Active geo-replication alone needs app connection changes.

11. Which feature lets you create up to four readable secondaries of a single Azure SQL database in other regions?

C. Active geo-replication is per database with up to four readable secondaries.

12. SQL Server on Azure VMs needs automatic failover between two VMs in different zones. Which feature?

B. Availability groups replicate databases synchronously and fail over automatically.

13. Which SQL Server HA/DR option protects the whole instance (logins, jobs, all databases) using shared storage?

A. An FCI fails over the entire instance; availability groups protect a set of databases.

14. In Azure, what's needed for clients to reach an availability group listener on VMs in a single subnet?

B. Azure networking doesn't support gratuitous ARP; use a load balancer or DNN, or put replicas in multiple subnets.

15. Which SQL option is simplest for warm-standby DR with an RPO of minutes and manual failover?

B. Log shipping restores transaction log backups on a secondary; failover is manual.

16. An on-premises SQL Server must use Azure as its DR site. Which is a valid hybrid design?

A. AG replicas can span on-premises and Azure (or a distributed AG). Async replication tolerates the latency.

17. Which Azure SQL Managed Instance feature can replicate from SQL Server for hybrid DR?

C. The MI link uses distributed availability groups to replicate from SQL Server to Managed Instance.

18. Which is generally true when comparing PaaS and IaaS for HA/DR?

A. On VMs you configure clustering, AGs and replication; PaaS services provide most of it.

19. A cheaper DR design for a non-critical database accepts an RPO of hours. Which option fits?

A. Geo-restore uses geo-replicated backups; RPO can be up to an hour or more, but it costs nothing extra.

20. Why should you test DR regularly?

D. A DR plan that has never been tested is a hope, not a plan. Test failovers (e.g. Site Recovery test failover) don't affect production.