Which of the below mentioned statements may not help the user understand the IP mechanism supported by ELB?

A user has configured ELB with two EBS backed EC2 instances. The user is trying to understand the DNS access and IP support for ELB.

Which of the below mentioned statements may not help the user understand the IP mechanism supported by ELB?
A .  The client can connect over IPV4 or IPV6 using Dualstack
B .  Communication between the load balancer and back-end instances is always through IPV4
C .  ELB DNS supports both IPV4 and IPV6
D .  The ELB supports either IPV4 or IPV6 but not both

View Answer

Answer: D

Explanation:

Elastic Load Balancing supports both Internet Protocol version 6 (IPv6) and Internet Protocol version 4 (IPv4). Clients can connect to the user’s load balancer using either IPv4 or IPv6 (in EC2-Classic) DNS. However, communication between the load balancer and its back-end instances uses only IPv4. The user can use the Dualstack-prefixed DNS name to enable IPv6 support for communications between the client and the load balancers. Thus, the clients are able to access the load balancer using either IPv4 or IPv6 as their individual connectivity needs dictate.

Reference: http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/UserScenariosForEC2.html