A client is using CloudFront with a source that normally serves dynamic content. There is a requirement that as soon the content is changed in the source, it is delivered to the client. Which of the following configuration can be made to fulfill this requirement?

Answer options:

A.Use the fast invalidate feature provided in CloudFront.
B.Set TTL to 10 seconds.
C.Set TTL to 0 seconds.
D.Dynamic content cannot be served from the CloudFront.
E.You have to contact the AWS support center to enable this feature.

Answer - C
In CloudFront, to enforce content delivery to the user as soon as it gets changed by the origin, the time to live (TTL) should be set to 0.
Option A is incorrect because invalidate is used to remove the content from CloudFront edge locations cache before it expires. The next time a viewer requests the object, CloudFront fetches the content from the origin; whereas, setting TTL to 0 enforces CloudFront to deliver the latest content as soon as the origin updates it.
Option B is incorrect because setting TTL to 10 will keep the content in the cache for some time even though the origin updates it.
Option C is CORRECT because setting TTL to 0 will enforce content delivery to the user as soon as it gets changed by the origin.
Option D is incorrect as CloudFront surely serves dynamic content.
Option E is incorrect as you do not have to contact the AWS support center for this scenario.
More information on TTL in CloudFront:
You can control how long your objects stay in a CloudFront cache before CloudFront forwards another request to your origin. Reducing the duration allows you to serve dynamic content. The low TTL is also given in the AWS documentation.
For more information on CloudFront dynamic content, please refer to the below URL:
http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html