A software development team just finished phase 1 of a web service that provides NBA news to subscribers. The web service has used a dedicated VPC which has only IPv4 CIDR (10.0.0.0/16) with two public subnets and two private subnets. A NAT gateway is put into each public subnet for outbound internet traffic. The EC2 instances are put into private subnets with a route that connects all Internet-bound IPv4 traffic to the relevant NAT gateway. The product is getting more and more popular and needs IPv6 to support some new features. Which below options are required for the new support for IPv6? Select 3.

Answer options:

A.Delete existing VPC and recreate a new VPC with both IPv4 and IPv6 CIDR. Create new public and private subnets with both IPv4 and IPv6 address ranges.
B.Associate an Amazon-provided IPv6 CIDR block with existing VPC and subnets. In the VPC and subnets console, choose “Add IPv6 CIDR”.
C.For public subnets, create a route that routes all IPv6 traffic from the subnet to the internet gateway. For private subnets, create a route that routes all Internet-bound IPv6 traffic to an egress-only internet gateway.
D.Update the route tables to route the IPv6 traffic. For public subnets, create a route that routes all IPv6 traffic from the subnet to the internet gateway. For private subnets, create a route that routes all Internet-bound IPv6 traffic to NAT gateway.
E.Assign IPv6 addresses to NAT gateway which will be used to route the internet-bound IPv6 traffic from EC2 instances.
F.Assign IPv6 addresses to EC2 instances from the IPv6 address range that is allocated to the subnet.

Correct Answer – B, C, F
 
Refer to https://docs.aws.amazon.com/vpc/latest/userguide/vpc-migrate-ipv6.html for the details on how to migrate to IPv6 traffic. Please also note that this question asks for the necessary options. The below steps are required.
Step 1: Associate an IPv6 CIDR Block with Your VPC and Subnets
Step 2: Update Your Route Tables
Step 3: Update Your Security Group Rules
Step 4: Change Your Instance Type
Step 5: Assign IPv6 Addresses to Your Instances
Option A is incorrect: Because you do not need to delete and recreate VPC to support IPv6.
Option B is CORRECT: Because that is a required step to add IPv6 CIDR in both VPC and subnets.
Option C is CORRECT: Because the routing table needs to be modified to route the IPv6 traffic properly.
Option D is incorrect: Because the NAT gateway is IPv4 only. For IPv6, an egress-only internet gateway should be used. Refer to https://docs.aws.amazon.com/vpc/latest/userguide/egress-only-internet-gateway.html.
Option E is incorrect: Same reason as option
D. Also, you cannot add IPv6 IP range to the NAT gateway.
Option F is CORRECT: Because EC2 instances need IPv6 addresses to route IPv6 traffic. This can be done in “Actions, Networking, Manage IP Addresses” and choose “Assign new IP” Under “IPv6 Addresses”.