You’ve just set up an Amazon Redshift cluster, and you want all COPY and UNLOAD traffic between your cluster and your data repositories to go through your Amazon VPC. You’ve noticed that the Internet is being utilized for the data being copied. You want to ensure that the internet is not used during the copy operation. How can you achieve this?

Answer options:

A.Ensure that the NACLs are set on the Subnets hosting the Redshift cluster.
B.Ensure that Enhanced VPC routing is enabled for the Redshift cluster.
C.Ensure that Security Groups are set on the EC2 Instances hosting the Redshift cluster.
D.Ensure that the routing table points to a VPN instead of the Internet gateway.

Answer – B
The AWS Documentation mentions the following.
When you use Amazon Redshift Enhanced VPC Routing, Amazon Redshift forces all COPY and UNLOAD traffic between your cluster and your data repositories through your Amazon VPC. You can now use standard VPC features, such as VPC security groups, network access control lists (ACLs), VPC endpoints, VPC endpoint policies, Internet gateways, and Domain Name System (DNS) servers, to tightly manage the flow of data between your Amazon Redshift cluster and other resources. When you use Enhanced VPC Routing to route traffic through your VPC, you can also use VPC flow logs to monitor COPY and UNLOAD traffic.
If Enhanced VPC Routing is not enabled, Amazon Redshift routes traffic through the Internet, including traffic to other services within the AWS network.
Options A and C are invalid because this has more to do with the Security aspect.
Option D would be the same solution and not avoid traffic flowing via the Internet.
For more information on Enhanced VPC Routing, just browse to the below URL:
https://docs.aws.amazon.com/redshift/latest/mgmt/enhanced-vpc-routing.html