ANS-C01 · Question #157
A company is deploying a web application into two AWS Regions. The company has one VPC in each Region. Each VPC has three Amazon EC2 instances as web servers behind an Application Load Balancer…
The correct answer is D. For each ALB, create an A record that has a latency-based routing policy to route. Explanation Option D is correct because latency-based routing in Route 53 automatically directs users to the AWS Region that provides the lowest network latency, and when configured with health checks on each ALB alias record, Route 53 will automatically fail over to the…
Question
A company is deploying a web application into two AWS Regions. The company has one VPC in each Region. Each VPC has three Amazon EC2 instances as web servers behind an Application Load Balancer (ALB). The company already has configured an Amazon Route 53 public hosted zone for example.com. Users will access the application by using the fully qualified domain name (FQDN) of app.example.com. The company needs a DNS solution that allows global users to access the application. The solution must route the users' requests to the Region that provides the lowest response time. The solution must fail over to the Region that provides the next-lowest response time if the application is unavailable in the initially intended Region. Which solution will meet these requirements?
Options
- AFor each ALB, create an A record that has a geolocation routing policy to route app.example.com
- BCreate an A record that has a geolocation routing policy to route app.example.com to the IP
- CCreate an A record that has a latency-based routing policy to route app.example.com as an alias
- DFor each ALB, create an A record that has a latency-based routing policy to route
How the community answered
(36 responses)- A8% (3)
- B3% (1)
- C14% (5)
- D75% (27)
Explanation
Explanation
Option D is correct because latency-based routing in Route 53 automatically directs users to the AWS Region that provides the lowest network latency, and when configured with health checks on each ALB alias record, Route 53 will automatically fail over to the next-lowest-latency Region if the primary becomes unhealthy - satisfying both the performance and failover requirements.
Why the distractors are wrong:
- Options A and B use geolocation routing, which routes traffic based on the user's geographic location (country/continent), not network latency - this does not guarantee the lowest response time, as a geographically close Region is not always the fastest.
- Option B additionally references routing to an IP address rather than an ALB alias, which is not a best practice for ALBs since their IPs can change dynamically.
- Option C is partially correct in using latency-based routing, but the phrasing suggests a single record rather than creating individual records for each ALB, which is necessary to properly represent both Regions and enable health-check-driven failover.
Memory Tip: Think "L for Latency = Lowest response time" - whenever an exam question mentions lowest response time or fastest performance, latency-based routing is your answer, not geolocation (which is purely map-based, not speed-based).
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