The correct answer is to use a custom origin header in the Route 53 latency policy to route based on the user's IP address and enable ALB stickiness. This works because Route 53’s latency-based routing evaluates DNS queries at the start of a session and can change the resolved region on subsequent queries if network conditions shift, but it has no built-in mechanism to remember a user’s previous region. By injecting a custom header that reflects the user’s source IP, you force the latency policy to consistently route that IP to the same regional endpoint, while the ALB’s stickiness ensures the user stays on the same backend instance within that region. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding that DNS-level routing (like latency) is stateless and session-unaware, making it a common trap to assume ALB stickiness alone prevents cross-region switching. A key memory tip: “DNS routes the request, but headers keep it local”—the custom origin header bridges the gap between stateless DNS and stateful application sessions.
ANS-C01 Network Management and Operations Practice Question
This ANS-C01 practice question tests your understanding of network management and operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 global company is designing a multi-region Active-Active application using Amazon Route 53 latency-based routing. Each region has an Application Load Balancer (ALB) fronting Auto Scaling groups. The application requires sticky sessions based on the user's source IP. The network team notices that users are frequently switched to a different region mid-session, causing errors. What should the team do to resolve this issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a custom origin header in the Route 53 latency policy to route based on the user's IP address and enable ALB stickiness
Option C is correct because Route 53 latency-based routing does not natively support sticky sessions; using a custom origin header with ALB stickiness ensures users stick to the correct regional endpoint. Option A is wrong because enabling ALB stickiness alone does not prevent Route 53 from switching regions. Option B is wrong because health checks do not affect routing decisions during a session. Option D is wrong because geolocation routing would not adapt to latency and may cause incorrect routing.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 Route 53 health checks with a low threshold to quickly detect failures
Why it's wrong here
Health checks do not address session continuity.
✗
Enable stickiness on each ALB using a cookie generated by the ALB
Why it's wrong here
Stickiness per ALB does not prevent Route 53 from switching regions.
✓
Use a custom origin header in the Route 53 latency policy to route based on the user's IP address and enable ALB stickiness
Why this is correct
Custom origin header and ALB stickiness provide session persistence.
Related concept
Static NAT maps one inside address to one outside address.
✗
Switch to geolocation routing policy with a bias to maintain sessions
Why it's wrong here
Geolocation routing does not consider latency and may not be optimal.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related ANS-C01 NAT questions on configuration and troubleshooting.
Network Management and Operations — This question tests Network Management and Operations — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Use a custom origin header in the Route 53 latency policy to route based on the user's IP address and enable ALB stickiness — Option C is correct because Route 53 latency-based routing does not natively support sticky sessions; using a custom origin header with ALB stickiness ensures users stick to the correct regional endpoint. Option A is wrong because enabling ALB stickiness alone does not prevent Route 53 from switching regions. Option B is wrong because health checks do not affect routing decisions during a session. Option D is wrong because geolocation routing would not adapt to latency and may cause incorrect routing.
What should I do if I get this ANS-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related ANS-C01 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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