SAP-C02 Design for New Solutions Practice Question

A company is migrating a legacy on-premises application to AWS. The application requires a fixed IP address for whitelisting by external partners. The solution must be highly available across multiple Availability Zones. Which design should they use?

⚠ Common exam trap

Candidates often assume an ALB can use Elastic IPs because it is a modern load balancer, but ALBs are DNS-based and cannot be assigned static IPs, making the NLB the only correct choice for fixed IP whitelisting with high availability.

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

✓

Use a Network Load Balancer (NLB) with an Elastic IP address.

A Network Load Balancer (NLB) supports static IP addresses via Elastic IPs per Availability Zone, providing a fixed IP for partner whitelisting while maintaining high availability across multiple AZs. Unlike ALBs, NLBs operate at Layer 4 and can preserve the client IP, which is critical for IP-based whitelisting scenarios.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Use an Application Load Balancer (ALB) with an Elastic IP address.
Why it's wrong here
ALB does not support Elastic IP; it uses a DNS name.
✗
Use Amazon Route 53 with a weighted routing policy.
Why it's wrong here
Route 53 is DNS, not a load balancer; does not provide a fixed IP.
✓
Use a Network Load Balancer (NLB) with an Elastic IP address.
Why this is correct
NLB supports Elastic IPs and is highly available across AZs.
✗
Use a Classic Load Balancer (CLB) with an Elastic IP address.
Why it's wrong here
CLB supports Elastic IP but is a legacy option; NLB is more modern and recommended.

Go deeper

SAP-C02 Design for New Solutions Practice Question

Why each option matters

Option-by-option breakdown

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