About This Flashcard Deck
This flashcard deck contains 10 cards covering key Performance & Troubleshooting concepts for the ANS-C01 exam. Test your knowledge of network optimization, bandwidth, placement groups, and connectivity troubleshooting. Use active recall by attempting to answer each question before revealing the answer. Research shows that flashcard-based active recall is one of the most effective study techniques for certification exams.
Question
What is EFA (Elastic Fabric Adapter)?
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Answer
Network device for HPC. Bypasses OS kernel for low-latency, high-throughput communication between instances. Supports MPI/NCCL. Linux only, cluster placement group.
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All Performance & Troubleshooting Flashcards
Q: What is EFA (Elastic Fabric Adapter)?
A: Network device for HPC. Bypasses OS kernel for low-latency, high-throughput communication between instances. Supports MPI/NCCL. Linux only, cluster placement group.
Q: Why might traffic between VPCs over TGW be asymmetric?
A: TGW sends traffic to any AZ in the destination VPC. Return path may use a different AZ. Enable appliance mode for stateful inspection to fix this.
Q: What is the MTU for traffic over VPN?
A: 1500 bytes maximum due to IPSec encapsulation overhead. Cannot use jumbo frames (9001 MTU) over VPN tunnels.
Q: What is the per-tunnel throughput for Site-to-Site VPN?
A: 1.25 Gbps per tunnel. Use ECMP over Transit Gateway (multiple VPN connections) to aggregate bandwidth beyond single tunnel limit.
Q: What causes a blackhole route in Transit Gateway?
A: Attachment is deleted but route remains, or static route points to non-existent attachment. Traffic is silently dropped. Check TGW route table for blackhole status.
Q: How do you troubleshoot Direct Connect connectivity?
A: Check: physical layer (light levels, CRC errors) → BGP session (state, prefixes) → route propagation → security groups/NACLs → VIF state in console.
Q: What is Reachability Analyzer?
A: Automated tool that tests connectivity between two points in your VPC network. Analyzes route tables, SGs, NACLs, and identifies the component blocking traffic.
Q: What is the bandwidth of a NAT Gateway?
A: 100 Gbps burst. If you need more, split resources across multiple subnets with separate NAT Gateways. 55,000 simultaneous connections per destination.
Q: How does cross-region VPC peering affect performance?
A: Traffic is encrypted, uses AWS backbone (not internet). Latency depends on geographic distance. No single point of bandwidth limit published. Billed per GB.
Q: What is Network Access Analyzer?
A: Identifies unintended network access by analyzing security groups, NACLs, route tables, and network paths against access requirements you define.