The answer is that client IP preservation for an NLB requires the target group to be of type 'instance' and the NLB must not be integrated with AWS Global Accelerator. This works because when the target group is instance-based, the NLB forwards packets with the original source IP address intact, bypassing network address translation so backend instances see the client directly. In contrast, IP-based target groups force the NLB to perform NAT to route to specified IP addresses, breaking preservation. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this concept tests your understanding of how NLB packet flow differs between target types, and a common trap is assuming IP-based targets also support preservation. Remember the memory tip: "Instance keeps the IP, IP loses the IP" — if the target group is instance, the client IP is preserved; if it’s IP, the NLB must NAT it away.
SOA-C02 Networking and Content Delivery Practice Question
This SOA-C02 practice question tests your understanding of networking and content delivery. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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 a Network Load Balancer (NLB) with a static IP address. The SysOps administrator needs to enable client IP preservation for the NLB so that backend instances see the original client IP. Which TWO conditions are required for client IP preservation to work?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The target group must be of type 'instance'.
Option A is correct because client IP preservation for a Network Load Balancer (NLB) requires the target group to be of type 'instance'. When the target group is instance-based, the NLB can forward packets with the original source IP address intact, allowing backend instances to see the client's IP directly. This is not supported when the target group is of type 'IP' because the NLB must perform NAT to route to the specified IP addresses.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The target group must be of type 'instance'.
Why this is correct
Instance targets preserve client IP; IP targets do not.
Related concept
Read the scenario before looking for a memorised answer.
Proxy protocol must be enabled on the target group.
Why it's wrong here
Proxy protocol adds an additional header but is not required for IP preservation.
✓
The NLB must not be integrated with AWS Global Accelerator.
Why this is correct
Global Accelerator would replace the client IP with its own.
Related concept
Read the scenario before looking for a memorised answer.
✗
Cross-zone load balancing must be enabled.
Why it's wrong here
Cross-zone is not required for IP preservation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse client IP preservation with Proxy Protocol, thinking that Proxy Protocol must be enabled for client IP preservation to work, when in fact Proxy Protocol is a separate mechanism used when the target group is of type 'IP' or when preservation is not supported.
Detailed technical explanation
How to think about this question
Client IP preservation works by the NLB not performing source NAT on incoming packets when the target group is instance-based; instead, it forwards the packet with the original source IP and destination IP of the target instance. This is possible because the NLB uses a flow hash to maintain stickiness and relies on the instance's ENI to receive traffic directly. A common real-world scenario is when backend applications require the original client IP for logging, security, or geolocation, and using instance targets avoids the need for Proxy Protocol or X-Forwarded-For headers.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Networking and Content Delivery — This question tests Networking and Content Delivery — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The target group must be of type 'instance'. — Option A is correct because client IP preservation for a Network Load Balancer (NLB) requires the target group to be of type 'instance'. When the target group is instance-based, the NLB can forward packets with the original source IP address intact, allowing backend instances to see the client's IP directly. This is not supported when the target group is of type 'IP' because the NLB must perform NAT to route to the specified IP addresses.
What should I do if I get this SOA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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