- A
Application Load Balancer
Correct. ALB supports WebSocket protocol natively and provides sticky sessions (session affinity) using cookies or source IP. It operates at Layer 7, making it ideal for real-time chat applications that require persistent connections and application-aware routing.
- B
Network Load Balancer
Why wrong: Incorrect. While NLB can forward WebSocket traffic at Layer 4 (TCP), it does not offer native WebSocket support or application-layer features like cookie-based sticky sessions. NLB is designed for ultra-low latency and extreme performance, not for application-level session management.
- C
Classic Load Balancer
Why wrong: Incorrect. Classic Load Balancer is a legacy service that works at Layer 4 and Layer 7, but it does not support the WebSocket protocol. Additionally, it lacks the advanced features of ALB and is not recommended for new applications.
- D
Amazon Route 53
Why wrong: Incorrect. Amazon Route 53 is a Domain Name System (DNS) service. It can direct traffic to endpoints using routing policies (e.g., latency-based) but does not function as a load balancer. It cannot maintain sticky sessions or handle WebSocket connections directly.
Quick Answer
The answer is the Application Load Balancer. This is correct because the ALB operates at Layer 7, natively supporting WebSocket connections and the long-lived, bidirectional communication they require, while its built-in sticky session feature uses a cookie to bind a client to a specific EC2 instance for the entire session. On the AWS Certified Cloud Practitioner CLF-C02 exam, this question tests your understanding of which load balancer handles application-layer protocols and session persistence, often appearing as a scenario about real-time apps like chat or gaming. A common trap is choosing the Network Load Balancer, which handles TCP traffic at Layer 4 but lacks native WebSocket support and sticky sessions at the application level. Remember the memory tip: ALB = Application Layer for WebSockets and Sticky Sessions.
CLF-C02 Cloud Technology and Services Practice Question
This CLF-C02 practice question tests your understanding of cloud technology and services. 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 real-time chat application that relies on long-lived WebSocket connections between clients and backend servers. The application runs on Amazon EC2 instances across multiple Availability Zones. The company needs a load balancer that can distribute incoming WebSocket traffic while preserving the connection and supporting sticky sessions. Which AWS load balancing solution should the company use?
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
Application Load Balancer
The Application Load Balancer (ALB) supports WebSocket connections natively at the application layer (Layer 7) and can maintain persistent connections via its built-in sticky session (session affinity) feature, which uses a cookie to bind a client to a specific target for the duration of the WebSocket session. This makes ALB the correct choice for a real-time chat application requiring long-lived WebSocket connections and sticky sessions across multiple Availability Zones.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
Why this is correct
Correct. ALB supports WebSocket protocol natively and provides sticky sessions (session affinity) using cookies or source IP. It operates at Layer 7, making it ideal for real-time chat applications that require persistent connections and application-aware routing.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Network Load Balancer
Why it's wrong here
Incorrect. While NLB can forward WebSocket traffic at Layer 4 (TCP), it does not offer native WebSocket support or application-layer features like cookie-based sticky sessions. NLB is designed for ultra-low latency and extreme performance, not for application-level session management.
- ✗
Classic Load Balancer
Why it's wrong here
Incorrect. Classic Load Balancer is a legacy service that works at Layer 4 and Layer 7, but it does not support the WebSocket protocol. Additionally, it lacks the advanced features of ALB and is not recommended for new applications.
- ✗
Amazon Route 53
Why it's wrong here
Incorrect. Amazon Route 53 is a Domain Name System (DNS) service. It can direct traffic to endpoints using routing policies (e.g., latency-based) but does not function as a load balancer. It cannot maintain sticky sessions or handle WebSocket connections directly.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume Network Load Balancer is the only option for WebSocket because it operates at Layer 4 and handles long-lived TCP connections, but they overlook that ALB explicitly supports WebSocket at Layer 7 and provides the required sticky session feature via cookies, which NLB lacks.
Detailed technical explanation
How to think about this question
Under the hood, ALB handles WebSocket upgrades by intercepting the HTTP Upgrade header (e.g., Upgrade: websocket) and then maintaining the TCP connection as a bidirectional tunnel between the client and the target EC2 instance, without inspecting further payload. The sticky session feature in ALB uses a generated cookie (AWSALB) that is set on the initial HTTP handshake, ensuring subsequent WebSocket frames are routed to the same instance even if the connection is re-established after a brief interruption.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Cloud Technology and Services — study guide chapter
Learn the concepts, then practise the questions
- →
Cloud Technology and Services practice questions
Targeted practice on this topic area only
- →
All CLF-C02 questions
1,024 questions across all exam domains
- →
AWS Certified Cloud Practitioner CLF-C02 study guide
Full concept coverage aligned to exam objectives
- →
CLF-C02 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related CLF-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Cloud Concepts practice questions
Practise CLF-C02 questions linked to Cloud Concepts.
Security and Compliance practice questions
Practise CLF-C02 questions linked to Security and Compliance.
Cloud Technology and Services practice questions
Practise CLF-C02 questions linked to Cloud Technology and Services.
Billing, Pricing, and Support practice questions
Practise CLF-C02 questions linked to Billing, Pricing, and Support.
AWS shared responsibility model practice questions
Practise CLF-C02 questions linked to AWS shared responsibility model.
AWS IAM practice questions
Practise CLF-C02 questions linked to AWS IAM.
AWS pricing practice questions
Practise CLF-C02 questions linked to AWS pricing.
AWS support plans practice questions
Practise CLF-C02 questions linked to AWS support plans.
AWS S3 practice questions
Practise CLF-C02 questions linked to AWS S3.
AWS EC2 practice questions
Practise CLF-C02 questions linked to AWS EC2.
Practice this exam
Start a free CLF-C02 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this CLF-C02 question test?
Cloud Technology and Services — This question tests Cloud Technology and Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Application Load Balancer — The Application Load Balancer (ALB) supports WebSocket connections natively at the application layer (Layer 7) and can maintain persistent connections via its built-in sticky session (session affinity) feature, which uses a cookie to bind a client to a specific target for the duration of the WebSocket session. This makes ALB the correct choice for a real-time chat application requiring long-lived WebSocket connections and sticky sessions across multiple Availability Zones.
What should I do if I get this CLF-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 11, 2026
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.