Objectives in this domain

Implement highly available architectures using Multi-AZ deployments, Elastic Load Balancing, Amazon Route 53 and loosely coupled designs.
Section 3.1medium
Implement scalable solutions using EC2 Auto Scaling, serverless compute, Amazon DynamoDB and decoupling with Amazon SQS and Amazon SNS.
Section 3.2medium
Scale and accelerate workloads with Amazon CloudFront, Amazon ElastiCache and Amazon API Gateway caching and request throttling.
Section 3.3medium
Select and automate disaster recovery strategies (backup and restore, pilot light, warm standby, multi-site active/active) to meet recovery time and recovery point objectives across Regions.
Section 3.4hard
Automate backup and recovery using AWS Backup, AWS Elastic Disaster Recovery, snapshots and cross-Region and cross-account replication.
Section 3.5medium

Sample question from this domain

Free sampleResilient Cloud Solutionsmedium

A team runs a stateful relational database for a payments service on a single Amazon RDS instance in one Availability Zone. A recent zonal hardware event took the database offline for over an hour, and the business now requires that an Availability Zone failure trigger an automatic failover with no application code changes and minimal recovery time. The team wants the lowest operational overhead while meeting this requirement. Which approach should they choose?

ACreate a cross-Region read replica of the RDS instance in a second AWS Region and promote that replica to a standalone primary manually whenever the original Availability Zone becomes unavailable.
BSchedule automated RDS snapshots every fifteen minutes and write a runbook so an operator can restore the latest snapshot into a healthy Availability Zone after an outage is detected.
CConvert the RDS instance to a Multi-AZ deployment so AWS maintains a synchronous standby in a second Availability Zone and automatically fails over to it when the primary Availability Zone is impaired. Correct
DAdd an in-Region RDS read replica in a second Availability Zone and point the application at the replica endpoint so reads continue if the primary Availability Zone fails.

Select RDS Multi-AZ when a single database must survive an Availability Zone failure with automatic failover and no application changes. An RDS Multi-AZ deployment provisions a synchronous standby in a separate Availability Zone and updates the DNS endpoint to the standby automatically when the primary is impaired, so applications reconnect to the same endpoint without code changes and recovery is measured in minutes.

Why A is wrong: A cross-Region read replica protects against Regional loss but promotion is a manual step that adds recovery time, and it addresses a different blast radius than the single-AZ failure the requirement actually targets.

Why B is wrong: Frequent snapshots reduce data loss but restoring one is a manual, slow operation that misses the automatic-failover and minimal-recovery-time requirement, leaving the service down while the restore runs.

Why C is correct: Multi-AZ keeps a synchronous standby in another Availability Zone and performs an automatic DNS-based failover on a zonal fault, meeting the requirement with no code change and the least operational overhead.

Why D is wrong: A read replica serves reads only and cannot accept writes without manual promotion, so a payments database that needs writes after an AZ loss is not protected by this design.

Other domains in this exam

SDLC Automation22% of the exam
Configuration Management and Infrastructure as Code17% of the exam
Monitoring and Logging15% of the exam
Incident and Event Response14% of the exam
Security and Compliance17% of the exam

See also the DOP-C02 cert hub, the study guide, and the cheat sheet.