Diagnose Route 53 failover with latency-based routing and weighted record sets

SAP-C02 By islever Editorial Last updated

Design a strategy to meet reliability requirements. Architect network connectivity strategies. Determine a strategy to improve reliability.

Short answer

DE Evaluate target health must be enabled on the latency record and health checks must be set up for the weighted record sets.

Question

A solutions architect has deployed a web application that serves users across two AWS Regions under a custom domain. The application uses Amazon Route 53 latency-based routing. The solutions architect has associated weighted record sets with a pair of web servers in separate Availability Zones for each Region. The solutions architect runs a disaster recovery scenario. When all the web servers in one Region are stopped, Route 53 does not automatically redirect users to the other Region. Which of the following are possible root causes of this issue? (Choose two.)
  1. The weight for the Region where the web servers were stopped is higher than the weight for the other Region.
  2. One of the web servers in the secondary Region did not pass its HTTP health check.
  3. Latency resource record sets cannot be used in combination with weighted resource record sets.
  4. The setting to evaluate target health is not turned on for the latency alias resource record set that is associated with the domain in the Region where the web servers were stopped. Correct Answer
  5. An HTTP health check has not been set up for one or more of the weighted resource record sets associated with the stopped web servers. Correct Answer

Key Takeaways

Route 53 does not health check targets unless a health check is associated with the record, and latency records only avoid unhealthy targets when Evaluate Target Health is enabled, so both the absence of health checks and the disabled setting can independently prevent the failover.

A web application is served across two Regions under a custom domain using Route 53 latency-based routing, with weighted record sets pointing to a pair of web servers in separate Availability Zones in each Region. In a DR test, stopping all web servers in one Region did not cause automatic redirection to the other Region.

Common mistake: Blaming the weight values. A higher weight on the stopped Region influences how Route 53 distributes traffic among healthy targets but does not by itself prevent failover, because weights are irrelevant once a target is not being returned as healthy. Latency-based and weighted record sets can also be combined, so that combination is not the defect.

Expert Analysis

Why the Answer Is Correct

Two independent configuration gaps can produce this behaviour. If evaluate target health is not turned on for the latency alias record associated with the Region whose servers were stopped, Route 53 has no signal to stop returning that endpoint, so latency-based routing keeps selecting it and never shifts users elsewhere. Separately, if an HTTP health check has not been set up for one or more of the weighted record sets pointing at the stopped web servers, Route 53 has nothing to mark those targets unhealthy, because weights alone do not detect failure. Either gap on its own is enough to prevent the automatic redirection observed in the test, which is why both are correct.

Why the Other Options Are Wrong

A: A higher weight on the stopped Region affects distribution among healthy targets, but a weight is a preference value and not a health signal, so it does not cause or prevent failover once a target is unhealthy. B: An unhealthy server in the secondary Region would reduce capacity there but would not prevent Route 53 from failing over away from the stopped primary Region, so it is not a root cause of the observed behaviour. C: Latency resource record sets can be used in combination with weighted resource record sets, so the combination itself is not invalid and is not the defect.

Community Comment Notes

The community voted 100 to 0 for D and E, and the top-voted comment linked the Route 53 documentation on complex failover configurations. Commenters consistently noted that Route 53 latency-based routing does not inherently perform health checks, so without health checks and the evaluate target health setting there is no automatic redirection.

Official Reference

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/dns-failover-complex-configs.html

This link opens the official vendor documentation in a new tab.

Community Votes

DE
100%

100% of anonymous learners picked answer DE. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 6 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 6

  1. trungtd 👍 4
    Route 53 latency-based routing does not inherently perform health checks. If a web server in one region goes down, Route 53 won't automatically redirect traffic to the other region unless health checks are properly configured and associated with your DNS records.
  2. kejam 👍 4
    Answer DE: An antique/classic question, answers are in a different order and wording slightly changed. https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/dns-failover-complex-configs.html
  3. 0b43291 👍 3
    D. The "Evaluate Target Health" setting is not enabled for the latency alias record set associated with the stopped Region. When using latency routing, this setting must be enabled so Route 53 considers the health status of associated resources and stops routing traffic to unavailable servers. E. HTTP health checks are not set up for one or more weighted record sets associated with the stopped web servers. Without health checks, Route 53 cannot detect unhealthy or unavailable servers and will continue routing traffic to them.
  4. Russs99 👍 1
    DE are the correct answers for the given scenario
  5. alexis123456 👍 2
    correct answer is D an E
Show 1 more comment
  1. career360guru 👍 1
    Option D and E

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