You currently have set up a VPN configuration from your on-premises location to AWS. Your AWS VPC has a CIDR of 10.0.0.0/16 and a subnet of 10.0.1.0/24. Your on-premises location has a network CIDR block of 10.0.37.0/24. The traffic is being dropped when it is being sent from the subnet instances to your on-premises location. Why could this be the most probable reason in this case?

Answer options:

A.You have not set Enhanced Networking on the Instances.
B.There is an overlap in prefixes.
C.The “Do not fragment” is set in the IP header.
D.The MTU is not set to 9001.

Answer – B
Such an example is given in the AWS Documentation.
Connections with Your Local Network and Other VPCs
You can optionally set up a connection between your VPC and your corporate or home network. If you have an IPv4 address prefix in your VPC that overlaps with one of your networks` prefixes, any traffic to the network`s prefix is dropped. For example, let`s say that you have the following:
A VPC with CIDR block 10.0.0.0/16
A subnet in that VPC with CIDR block 10.0.1.0/24
Instances running in that subnet with IP address 10.0.1.4 and 10.0.1.5
On-premises host networks using CIDR blocks 10.0.37.0/24
When those instances in the VPC try to talk to hosts in the 10.0.37.0/24 address space, the traffic is dropped because 10.0.37.0/24 is part of the larger prefix assigned to the VPC (10.0.0.0/16).
Options A, C, and D are incorrect as there are no suggestions on the type of traffic being sent.
For more information on VPC and Subnets, please refer to the below URL
https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Subnets.html