Quick Answer
The answer is the Elastic Fabric Adapter (EFA). EFA is the correct choice because it provides OS-bypass capabilities through the Libfabric library, allowing HPC applications to communicate directly with the network interface without kernel intervention, which is critical for achieving the microsecond-level latency required for tightly coupled inter-node communication in genomics research using MPI. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this question tests your understanding of specialized networking for HPC workloads, often appearing as a distractor against Elastic Network Adapter (ENA) or AWS Direct Connect—remember that ENA lacks OS-bypass and is for standard networking, not low-latency inter-node communication. A common trap is selecting ENA for its high bandwidth, but EFA is the only AWS solution designed for tightly coupled HPC clusters requiring low-latency inter-node communication. Memory tip: EFA = “Eliminates For Application” kernel overhead, enabling fast, direct data paths.
This SAP-C02 practice question tests your understanding of design for new solutions. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is building a high-performance computing (HPC) cluster on AWS for genomics research. The compute nodes require low-latency inter-node communication. Which networking solution should be used?
Elastic Fabric Adapter (EFA)
EFA provides low-latency, high-throughput inter-node communication for HPC.
Enhanced Networking (ENA)
Why wrong: ENA provides higher performance but not the ultra-low latency that EFA provides for HPC.
VPC Peering
Why wrong: VPC Peering is for connecting VPCs, not for inter-node communication within a cluster.
AWS Direct Connect
Why wrong: Direct Connect connects on-premises to AWS, not inter-node.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Elastic Fabric Adapter (EFA)
Elastic Fabric Adapter (EFA) is a network interface that enables HPC and machine learning applications to achieve low-latency inter-node communication by bypassing the operating system kernel and providing OS-bypass capabilities via the Libfabric library. This is essential for tightly coupled HPC workloads like genomics research, where MPI (Message Passing Interface) jobs require microsecond-level latency and high throughput between compute nodes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Elastic Fabric Adapter (EFA)
Why this is correct
EFA provides low-latency, high-throughput inter-node communication for HPC.
Related concept
Read the scenario before looking for a memorised answer.
Enhanced Networking (ENA)
Why it's wrong here
ENA provides higher performance but not the ultra-low latency that EFA provides for HPC.
VPC Peering
Why it's wrong here
VPC Peering is for connecting VPCs, not for inter-node communication within a cluster.
AWS Direct Connect
Why it's wrong here
Direct Connect connects on-premises to AWS, not inter-node.
Common exam traps
The trap here is that candidates confuse Enhanced Networking (ENA) with Elastic Fabric Adapter (EFA), assuming both provide similar low-latency benefits, but only EFA offers OS-bypass for HPC inter-node communication, while ENA still relies on kernel processing.
Detailed technical explanation
EFA uses a custom Elastic Network Adapter (ENA) driver combined with the Libfabric user-space library to enable applications to send and receive data directly to/from the network interface without kernel involvement, reducing latency to single-digit microseconds. Under the hood, EFA supports Reliable Datagram (RD) and Unreliable Datagram (UD) transport modes, and it integrates with AWS ParallelCluster and Slurm to automatically configure MPI and NCCL (NVIDIA Collective Communications Library) for optimal performance. A real-world scenario is a genomics workload using GROMACS or BWA-MEM that scales across hundreds of instances; without EFA, the MPI all-to-all communication would become a bottleneck due to kernel overhead.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
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FAQ
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
The correct answer is: Elastic Fabric Adapter (EFA) — Elastic Fabric Adapter (EFA) is a network interface that enables HPC and machine learning applications to achieve low-latency inter-node communication by bypassing the operating system kernel and providing OS-bypass capabilities via the Libfabric library. This is essential for tightly coupled HPC workloads like genomics research, where MPI (Message Passing Interface) jobs require microsecond-level latency and high throughput between compute nodes.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This SAP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAP-C02 exam.
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