Currently, you`re responsible for the design and architect of a highly available application. After building the initial environment, you discover that your application does not work correctly until port 443 is added to the security group. After adding port 443 to the appropriate security group, how much time will it take for the application to work correctly? 

Answer options:

A.Generally, it takes 2-5 minutes for the rules to propagate.
B.Immediately after a reboot of the EC2 Instances, belonging to that security group.
C.Changes apply instantly to the security group, and the application should be able to respond to 443 requests.
D.It will take 60 seconds for the rules to apply to all Availability Zones within the region.

Correct Answer – C
This is given in the AWS Documentation:
"Some systems for setting up firewalls let you filter on source ports. Security groups let you filter only on destination ports.
When you add or remove rules, they are automatically applied to all instances associated with the security group".
For more information on Security Groups, please refer to the below link:
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_SecurityGroups.html