How can the organization configure that a request from …

An organization is setting a website on the AWS VPC. The organization has blocked a few IPs to
avoid a D-DOS attack.
How can the organization configure that a request from the above mentioned IPs does not access
the application instances?

A.
Create an IAM policy for VPC which has a condition to disallow traffic from that IP address.

B.
Configure a security group at the subnet level which denies traffic from the selected IP.

C.
Configure the security group with the EC2 instance which denies access from that IP address.

D.
Configure an ACL at the subnet which denies the traffic from that IP address.

Explanation:
A Virtual Private Cloud (VPC) is a virtual network dedicated to the user’s AWS account. It enables
the user to launch AWS resources into a virtual network that the user has defined. AWS provides
two features that the user can use to increase security in VPC: security groups and network
ACLs. Security group works at the instance level while ACL works at the subnet level. ACL allows
both allow and deny rules. Thus, when the user wants to reject traffic from the selected IPs it is

recommended to use ACL with subnets.
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_ACLs.html