Your team has just finished developing a new version of an existing application. This is a web-based application hosted on AWS. Currently, Route 53 is being used to point the company’s DNS name to the web site. Your Management has instructed you to deliver the new application to a portion of the users for testing. How can you achieve this?

Answer options:

A.Port the application onto Elastic beanstalk and use the Swap URL feature.
B.Use Route 53 weighted Routing policies.
C.Port the application onto Opswork by creating a new stack.
D.Use Route 53 failover Routing policies.

Answer – B
The AWS Documentation mentions the following to support this.
Weighted Routing
Weighted routing lets you associate multiple resources with a single domain name (example.com) or subdomain name (acme.example.com) and choose how much traffic is routed to each resource. This can be useful for various purposes, including load balancing and testing new versions of software.
To configure weighted routing, you create records that have the same name and type for each of your resources. You assign each record a relative weight that corresponds with how much traffic you want to send to each resource. Amazon Route 53 sends traffic to a resource based on the weight that you assign to the record as a proportion of the total weight for all records in the group:
Formula for how much traffic is routed to a given resource: 
 weight for a specified record/sum of the weights for all records.
For example, if you want to send a tiny portion of your traffic to one resource and the rest to another resource, you might specify weights of 1 and 255. The resource with a weight of 1 gets 1/256th of the traffic (1/1+255), and the other resource gets 255/256ths (255/1+255). You can gradually change the balance by changing the weights. If you want to stop sending traffic to a resource, you can change the weight for that record to 0.
Options A and C is incorrect since this would cause a full flown deployment of the new app and is just a maintenance overhead to port the application to a new service environment.
Option D is incorrect since this should only be used for failover conditions.
For more information on the weighted routing policy, please refer to the below Link-
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-weighted