Routing Policy for Degraded Service

Correct Answer - C.

Failover routing policy is the most appropriate routing policy to implement because it will make it possible for traffic to be routed to the resource in good health and not to the one experiencing poor response times.

Several instances can be configured.

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-failover

Option A is INCORRECT because the Geolocation routing policy is essential when traffic to the hosted resources is routed according to its originating source address.

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-geo

Option B is INCORRECT because a weighted routing policy can distribute request traffic amongst resources.

But in this scenario, it would be undesirable and cumbersome to manually set weights (preferences) each time any resource is unhealthy.

This will not be the most appropriate routing policy.

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-weighted

Option D is INCORRECT because latency-based routing policy allows for queries to be served by the resources with the shortest response times to the user's location.

The routing policy does not give the required functionality in the scenario.

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-latency

The most appropriate routing policy to implement in Amazon Route 53 for a web application co-located in two geographically distinct locations that is experiencing degraded service in one of the locations is the failover routing policy.

The failover routing policy is designed to route traffic to a specified resource only when it is healthy or available. In this case, the web application in the healthy location would be the primary resource and the one in the degraded location would be the secondary resource.

When using the failover routing policy in Amazon Route 53, you can configure a health check for the primary resource to monitor its health status. If the primary resource becomes unavailable, Amazon Route 53 can automatically switch traffic to the secondary resource.

This routing policy is particularly useful for scenarios where you have redundant resources deployed in different locations or availability zones. It helps to ensure that your application is available and responsive to users, even in the event of a localized service disruption.

In contrast, the geolocation routing policy is used to route traffic based on the location of the user, while the weighted routing policy is used to distribute traffic between resources based on a specified weight value. The latency-based routing policy routes traffic to the resource with the lowest latency based on the user's location.

Therefore, the failover routing policy is the most appropriate routing policy to use in this scenario as it ensures that traffic is routed to the healthy resource, while allowing for automatic failover in the event of an outage or degradation of service in one of the locations.