You currently have set up a VPC, route tables with routes defined for traffic and Subnets in AWS. You just want to establish communication across all hosts. But you notice that some applications are not working as desired. These are Ipv6 based applications that are sitting across subnets in the VPC. What must be done to alleviate this issue?

Answer options:

A.Ensure that the route of 0.0.0.0/0 is removed and a more specific route is placed.
B.Remove the route of 0.0.0.0/0 and add the route of ::/0 instead to allow all communication.
C.Add a route for ::/0 to the route table as well.
D.Add the default route of 172.132.0.0/16 to the Route table

Answer – C
The AWS Documentation mentions the following.
CIDR blocks for IPv4 and IPv6 are treated separately. For example, a route with a destination CIDR of 0.0.0.0/0 (all IPv4 addresses) does not automatically include all IPv6 addresses. You must create a route with a destination CIDR of ::/0 for all IPv6 addresses.
Options A and B are invalid since this would then stop communication for instances for Ipv4.
Option D is invalid because this CIDR block is not mentioned in the question.
For more information on Route propagation, one can visit the below URL
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Route_Tables.html