Question 555 of 1,748
Infrastructure SecuritymediumMultiple ChoiceObjective-mapped

SCS-C02 Proxy Protocol v2 Practice Question

This SCS-C02 practice question tests your understanding of infrastructure security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. A key principle to apply: proxy Protocol v2. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A company uses Network Load Balancer (NLB) in front of a fleet of EC2 instances in private subnets. Security team requires that the source IP addresses of clients be preserved in the access logs of the backend instances. Which configuration should the security engineer verify?

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

Configure proxy protocol v2 on the target group

Option A is correct because Network Load Balancer can preserve client source IP by enabling proxy protocol v2 on the target group. This adds a header containing the original client IP, which backend instances can log. Option B is incorrect because NLB can preserve source IP even when targets are in different subnets if proxy protocol is used. Options C and D do not affect source IP preservation.

Key principle: Proxy Protocol v2

Answer analysis

Option-by-option breakdown

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

  • Configure proxy protocol v2 on the target group

    Why this is correct

    Correct. Proxy protocol v2 preserves client source IP by adding a header that backend instances can parse and log.

    Related concept

    Proxy Protocol v2

  • Ensure the NLB is configured with a subnet from each Availability Zone and the targets are in the same subnets

    Why it's wrong here

    Incorrect. While placing targets in the same subnets as the NLB can help preserve source IP without proxy protocol, it is not a requirement. The condition stated in this option is not necessary for source IP preservation.

  • Enable target group stickiness

    Why it's wrong here

    Incorrect. Target group stickiness is for session persistence, not source IP preservation.

  • Enable cross-zone load balancing on the NLB

    Why it's wrong here

    Incorrect. Cross-zone load balancing distributes traffic across Availability Zones, but does not preserve source IP.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Candidates often assume that subnet alignment is required for source IP preservation with NLB. However, if targets are in different subnets, proxy protocol can still preserve the client IP.

Detailed technical explanation

How to think about this question

Under the hood, when an NLB forwards traffic to targets in the same subnet, it uses the same network interface (ENI) for both the listener and the target, so the source IP remains the original client IP. If targets are in different subnets, the NLB must route traffic through its own ENI, which performs source NAT (SNAT) to the NLB's private IP. This behavior is defined by AWS VPC networking and is independent of Proxy Protocol, which is an optional enhancement for passing metadata.

KKey Concepts to Remember

  • Proxy Protocol v2
  • Network Load Balancer (NLB)

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Proxy Protocol v2

Real-world example

How this comes up in practice

A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

What to study next

Got this wrong? Here's your next step.

Review proxy Protocol v2, then practise related SCS-C02 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this SCS-C02 question test?

Infrastructure Security — This question tests Infrastructure Security — Proxy Protocol v2.

What is the correct answer to this question?

The correct answer is: Configure proxy protocol v2 on the target group — Option A is correct because Network Load Balancer can preserve client source IP by enabling proxy protocol v2 on the target group. This adds a header containing the original client IP, which backend instances can log. Option B is incorrect because NLB can preserve source IP even when targets are in different subnets if proxy protocol is used. Options C and D do not affect source IP preservation.

What should I do if I get this SCS-C02 question wrong?

Review proxy Protocol v2, then practise related SCS-C02 questions on the same topic to reinforce the concept.

What is the key concept behind this question?

Proxy Protocol v2

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Last reviewed: Jul 4, 2026

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This SCS-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 SCS-C02 exam.