A customer has established an AWS Direct Connect connection to AWS. The link is up and routes are being advertised from the customer’s end. However, the customer cannot connect from EC2 instances inside its VPC to servers residing in its data center.

Answer options:

A.Add a route to the route table with an IPsec VPN connection as the target.
B.Enable route propagation to the Virtual Private Gateway (VGW).
C.Open the port 80 in the security group of the Virtual Private Gateway (VGW).
D.Modify the route table of all Instances using the ‘route’ command.
E.Enter the IPv4 destination addresses for routing the traffic over VGW.

Answers - B & E
Option A is incorrect because adding an option of VPN is unnecessary.
Option B is CORRECT because VGW is the other side of the connection (on the AWS side) and the route propagation needs to be enabled for the Direct Connect to work.
Option C is incorrect because there is no such configuration in the Virtual Private Gateway.
Option D is incorrect because there is no “route” command available on the instances in the VPC.Option E is correct because to advertise prefixes to Amazon, for Prefixes you want to advertise, enter the IPv4 CIDR destination addresses (separated by commas) to which traffic should be routed over the virtual interface. ( under Additional Settings )
https://docs.aws.amazon.com/directconnect/latest/UserGuide/routing-and-bgp.html