SAP-C02 Practice Question: Accelerate Workload Migration and Modernization
A company is migrating a critical application to AWS and needs to ensure high availability across two Availability Zones. The application runs on EC2 instances behind an Application Load Balancer (ALB). The database is an on-premises SQL Server that will be migrated later. Which architecture provides high availability for the application tier during the migration?
⚠ Common exam trap
The trap is confusing high availability with auto scaling or DNS-based routing; candidates may pick a single-AZ Auto Scaling group or Route 53 weighted routing, but true high availability across AZs requires a load balancer with cross-zone enabled.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Deploy EC2 instances in two AZs behind an ALB with cross-zone load balancing enabled.
Deploying EC2 instances in two Availability Zones behind an Application Load Balancer with cross-zone load balancing enabled provides high availability for the application tier. The ALB distributes traffic across healthy instances in both AZs, and cross-zone load balancing ensures even distribution even if one AZ has more instances. This architecture survives an AZ failure because the ALB routes traffic to the remaining AZ, and the application remains available.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Deploy EC2 instances in two AZs behind an ALB with cross-zone load balancing enabled.
Why this is correct
Instances in two Availability Zones behind an ALB survive an AZ failure, and cross-zone load balancing distributes requests evenly to healthy targets in the remaining zone. This delivers application-tier high availability during the migration, independent of the on-premises SQL Server still in place.
- ✗
Deploy EC2 instances in a single AZ with an Auto Scaling group.
Why it's wrong here
A single Availability Zone gives no AZ-level redundancy, so an AZ failure takes the application tier down regardless of the Auto Scaling group. Auto Scaling is tempting because it maintains instance count and replaces unhealthy instances, but it operates within whichever AZs are configured, and one AZ cannot satisfy the two-AZ requirement.
- ✗
Deploy EC2 instances in two AZs behind a Network Load Balancer (NLB).
Why it's wrong here
An NLB operates at layer 4 and cannot evaluate HTTP host or path rules, and the stem already specifies an Application Load Balancer for the application tier. NLB is tempting for high-throughput or static-IP TCP workloads, but replacing the ALB does not address the two-AZ requirement the architecture must meet.
- ✗
Use Amazon Route 53 weighted routing to distribute traffic to instances in two AZs.
Why it's wrong here
Route 53 weighted routing splits traffic by configured proportions, not by health-checked failover across AZs, and it bypasses the ALB entirely. It is tempting because it distributes traffic across endpoints, but weighted records suit gradual traffic shifting or A/B testing, not maintaining application-tier availability when an AZ fails.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SAP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAP-C02 exam.