CLF-C02 Cloud Technology and Services Practice Question
A company is deploying a multi-tier application on AWS. Which AWS service provides layer 4 (TCP/UDP) load balancing with ultra-high performance and static IP addresses?
⚠ Common exam trap
Watch out — candidates often confuse ALB's Layer 7 features with NLB's Layer 4 capabilities, or assume Classic Load Balancer still provides static IPs, but only NLB offers both Layer 4 operation and static IP addresses for ultra-high performance scenarios.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Network Load Balancer (NLB)
Network Load Balancer (NLB) operates at Layer 4 (TCP/UDP) and is designed to handle millions of requests per second with ultra-low latency. It provides static IP addresses per Availability Zone, which is essential for applications requiring fixed endpoints for whitelisting or DNS stability.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Application Load Balancer (ALB)
Why it's wrong here
Application Load Balancer (ALB) operates at Layer 7, meaning it makes routing decisions based on HTTP/HTTPS attributes such as URL paths, headers, and hostnames—ideal for microservices and containerized apps, but it cannot natively load balance raw TCP or UDP traffic. Furthermore, ALB endpoints are DNS-based and do not provide static Elastic IP addresses per Availability Zone, so clients cannot rely on fixed, whitelist-friendly IPs. Because the scenario demands Layer 4 protocol support and stable IP addresses, ALB is unsuitable.
- ✓
Network Load Balancer (NLB)
Why this is correct
Network Load Balancer (NLB) functions at Layer 4 of the OSI model, handling millions of requests per second with ultra-low latency while preserving the client's source IP address, which is critical for security and audit requirements. It automatically allocates one static Elastic IP per Availability Zone, giving clients immutable endpoints that remain unchanged even as backend capacity scales. This combination of TCP/UDP support, static IPs, and massive throughput makes NLB the precise match for this high-performance, fixed-IP load-balancing need.
- ✗
Gateway Load Balancer (GWLB)
Why it's wrong here
Gateway Load Balancer (GWLB) is a special-purpose AWS service that transparently sits in the network data path only to route traffic through third-party virtual appliances such as firewalls, intrusion detection/prevention systems, and deep-packet inspection tools. It uses GENEVE encapsulation and is not designed to be a general-purpose application load balancer that distributes user traffic to application servers or that provides static Elastic IP endpoints for client connectivity. Therefore, GWLB fails the scenario's requirement for straightforward TCP/UDP load balancing with stable IPs.
- ✗
Classic Load Balancer
Why it's wrong here
Classic Load Balancer is the legacy load balancer from AWS's earlier generation, and it lacks the advanced capabilities needed for modern, high-performance workloads. It does not offer static Elastic IP addresses per Availability Zone—its DNS name changes as instances scale—and it provides limited protocol support and only basic features compared to NLB. Old architecture, poor scalability, no source-IP preservation, and inability to supply stable IPs make it an outdated and incorrect choice for this TCP/UDP load-balancing requirement.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CLF-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 CLF-C02 exam.