You have been assigned the task of architecting an application in AWS. The architecture would consist of EC2, the Classic Load Balancer, Auto Scaling, and Route 53. You need to ensure that Blue-Green deployments are possible in this architecture. Which routing policy should you ideally use in Route 53 to achieve Blue-Green deployments?

Answer options:

A.Simple
B.Multivalue Answer
C.Latency
D.Weighted

Correct Answer – D
AWS Documentation mentions that the Weighted routing policy is good for testing new versions of the software. Also, It is the ideal approach for Blue-Green deployments.
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 the software.
For more information on Route 53 routing policies, please visit the following URL-
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html
Note: Multivalue-answer is recommended to use only when you want to route traffic randomly to multiple resources, such as web servers. You can create one multivalue answer record for each resource and, optionally, associate an Amazon Route 53 health check with each record.
However, in this case, we need to choose how much traffic is routed to each resource (blue and green). For example, Blue is currently live, and we need to send less portion of traffic to Green to check everything works fine. If yes, then we can decide to go with Green resources. If no, we can change the weight for that record to 0. Blue will be completely live again. 
NOTE:
When you implement the Blue-Green Deployment, it`s not always fixed that the Blue environment is in an Alive state and the Green environment in an Idle state vice versa. During the testing phase, you can route your traffic to both the Blue and Green environments with a specified traffic load.
For more information, please visit the link below.
https://d1.awsstatic.com/whitepapers/AWS_Blue_Green_Deployments.pdf (11 of 35). AWS explained with the proper diagram.