AmazonAmazon Advanced Networking Specialty ANS-C01 Certification·EN·Updated 3 Aug 2026
A network engineer must provide dual-stack connectivity (IPv4 and IPv6) between the company office and an AWS account. The on-premises router and the VPC both support dual-stack. The company has two AWS Direct Connect circuits to the office. The connection must be highly available and reliable for latency-sensitive traffic. Which choices satisfy these requirements? (Choose two.)
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Correct answer: Create a single private virtual interface (VIF) on each Direct Connect circuit. Add both IPv4 and IPv6 BGP peerings to that private VIF. Configure the on-premises device with the AWS-provided BGP neighbor addresses to advertise IPv4 routes on the IPv4 peering and IPv6 routes on the IPv6 peering. Enable Bidirectional Forwarding Detection (BFD) on every peering session., Create two private VIFs on each Direct Connect circuit: one private VIF for the IPv4 address family and one private VIF for the IPv6 address family. Configure the on-premises device with the AWS-provided BGP neighbor addresses so it advertises IPv4 routes over the IPv4 peering and IPv6 routes over the IPv6 peering. Enable Bidirectional Forwarding Detection (BFD) on every peering session..
Why this is the answer
Both correct options provide dual-stack connectivity over highly available Direct Connect circuits with BFD for fast failure detection, crucial for latency-sensitive traffic.
The first correct option uses a single private VIF per Direct Connect circuit, which supports both IPv4 and IPv6 BGP peerings simultaneously. This is a common and efficient configuration for dual-stack.
The second correct option uses two private VIFs per Direct Connect circuit, one dedicated to IPv4 and one to IPv6. While requiring more VIFs, this also achieves the dual-stack connectivity and high availability requirements.
The incorrect options either do not support dual-stack correctly (e.g., only IPv4 peering or incorrect route advertisement), do not enable BFD (which is essential for fast failover for latency-sensitive traffic), or incorrectly suggest reducing BGP hello timers instead of using BFD for rapid detection.