AmazonAmazon Advanced Networking Specialty ANS-C01 Certification·EN·Updated 3 Aug 2026
A company deploys an application across five VPCs attached to a transit gateway. Instances in each VPC must be able to register dynamically to receive multicast streams. How should a network engineer configure AWS resources to support dynamic multicast registration and delivery?
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Correct answer: Create an Internet Group Management Protocol (IGMP) multicast domain within the transit gateway. Associate the VPCs and applicable subnets with the multicast domain. Register the multicast senders' network interface with the multicast domain. Adjust the network ACLs to allow UDP traffic from the source to all receivers and to allow UDP traffic that is sent to the multicast group address..
Why this is the answer
The correct option leverages IGMP multicast domains, which are essential for dynamic multicast registration, allowing receivers to join and leave multicast groups as needed. Multicast traffic primarily uses UDP, making the allowance for UDP traffic in Network ACLs crucial. The main incorrect options either specify a "static source multicast domain," which does not support dynamic registration, or incorrectly state that TCP traffic should be allowed. Multicast is a UDP-based protocol, so configuring TCP in the ACLs would prevent the traffic from flowing correctly.