A CloudFront distribution delivers the web content of an application. Some static files are cached in the CloudFront distribution, and the TTL is set to 1 day. You upgrade the origin server, and a configuration JSON file is updated. However, when users access the website, the old file cached in CloudFront is returned, and some services are impacted. How would you resolve this problem?

Answer options:

A.Wait for a day and the file will be updated automatically.
B.Invalidate the object in CloudFront so that the object is removed from the CloudFront edge cache.
C.Modify the default TTL to be 0 in the CloudFront cache setting.
D.Upgrade the origin application again and add a cache-control header to inform CloudFront to remove the JSON file from its cache.

Correct Answer – B
Option A is incorrect because, with the method, the service will be impacted for a day. A better approach is to invalidate the object from the cache.
Option B is CORRECT because invalidating the object removes it from the CloudFront edge cache to return the correct file to the user. The issue can be resolved immediately with this method.
Option C is incorrect because the default TTL impacts all objects served by the CloudFront distribution. In this scenario, there is only 1 file that needs to be cleared from the cache.
Option D is incorrect because the application has to be upgraded again, which is unnecessary. Option B is faster and simpler.
Reference:
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Invalidation.html.