Reference Material:

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