Your organization had set up a web application on AWS VPC with 4 EC2 instances in a private subnet. They had configured an elastic load balancer to distribute traffic between all 4 EC2 instances. They decided to route traffic from the internet to the elastic load balancer resource via the domain, “www.example-web-application.com” they had already registered. Which type of record set do you need to create in Route 53?

Answer options:

A.A - IPv4 Address with Alias=NO and select the ELB resource
B.A - IPv4 Address with Alias=YES and select the ELB resource
C.CNAME - Canonical Name with ALIAS=NO and select the ELB IP addresses
D.CNAME - Canonical Name with ALIAS=YES and select the ELB resource

Answer: B
While using an Alias record to route traffic to AWS resources, Route 53 automatically recognizes the change in the resource eg an IP change in a Load Balancer will prompt route 53 to automatically send queries to the new IP address
Alias routing comes at no additional cost as compared to CNAME routing which incurs cost depending on the nature of its routing queries.
A CNAME record redirects DNS queries for a record name regardless of the record type specified in the DNS query, such as A or AAAA.Option A is incorrect because for A record, when Alias is not enabled, an IP address needs to be configured. For an ELB resource, this is not applicable.
Option B is CORRECT because when Alias is enabled in A record, you can select the ELB resource in the target. Route 53 responds to a DNS query only when the name of the alias record (such as xyz.example.com) and the type of the alias record (such as A or AAAA) match the name and type in the DNS query.
Option C is incorrect because, for a CNAME record, you need to configure a DNS name instead of an IP address.
Option D is incorrect because the CNAME Alias record does not support ELB resources.
`CNAME record with Alias=Yes` can work for the scenario given in the question, but it is not best suitable. Please check the youtube link given below.
https://www.youtube.com/watch?v=YPNzeuNd-lA
References:
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-to-elb-load-balancer.html
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resource-record-sets-choosing-alias-non-alias.html