Enable Multicast for Stock Ticker Application

Correct Answer - D.

To have multicast enabled between two EC2 instances within a VPC, a software VPN can have multicast communication between these two instances in different regions.

Options A & B are incorrect as This will create additional configuration changes & will allow all instances in Region eu-west-1 to communicate with region eu-west-2 unless control is set.

Option C is incorrect as although this will work this will allow all instances in each VPC to communicate with each other.

Since only one instance needs to communicate with other instances, additional control needs to be done on routing / Security Groups.

For more information on using software VPN appliances, refer to the following URL.

https://aws.amazon.com/blogs/networking-and-content-delivery/integrating-external-multicast-services-with-aws/ https://aws.amazon.com/answers/networking/aws-multiple-region-multi-vpc-connectivity/

The requirement is to enable multicast for a new stock ticker application installed on EC2 instances in eu-west-1 and eu-west-2 regions for a London-based stockbroking firm, which has set up multiple VPCs in these regions with Direct Connect enabled from the head office.

Option A suggests creating a VPN from an instance in eu-west-1 to the corporate office and using the existing Direct Connect connectivity from the corporate office to VPC in eu-west-2 Region. However, this solution does not enable multicast between the EC2 instances in the two regions, as VPNs do not support multicast traffic.

Option B suggests creating a separate VPN at each region from the corporate office and allowing communication between two instances over the corporate network. This solution is not optimal as it requires multiple VPNs, increasing management overhead and costs.

Option C suggests creating an inter-region VPC peering between VPCs in two different regions. This solution enables multicast traffic between the EC2 instances in the two VPCs as it creates a secure and private network connection between them. However, VPC peering does not support multicast traffic by default. A custom solution would need to be implemented, such as using a third-party software solution or implementing multicast over unicast.

Option D suggests creating a software VPN between instances in two VPCs in two different regions. This solution enables multicast traffic between the EC2 instances in the two VPCs as it creates a secure and private network connection between them, and software VPNs can support multicast traffic. However, this solution can be complex to set up and manage.

Therefore, the most cost-effective solution that meets the requirement of enabling multicast for a new stock ticker application installed on EC2 instances in eu-west-1 and eu-west-2 regions would be to create an inter-region VPC peering between VPCs in two different regions (Option C) and implementing multicast over unicast.