ANS-C01 Question 65
Select 3You have a web application hosted on Amazon EC2 instances behind an Application Load Balancer (ALB). You also have an internal service that communicates with the web tier using a Network Load Balancer (NLB). Which of the following statements correctly describe how the load balancers operate at different OSI layers?
- A
The Application Load Balancer operates at Layer 7 of the OSI model, enabling content-based routing based on HTTP headers.
- B
The Network Load Balancer operates at Layer 4 of the OSI model, routing traffic based on IP addresses and TCP/UDP ports.
- C
The Application Load Balancer operates at Layer 3 of the OSI model, distributing traffic based on source and destination IP addresses.
- D
The Network Load Balancer operates at Layer 7 of the OSI model, enabling content-based routing for backend services.
- E
The Network Load Balancer is well-suited for handling millions of requests per second with ultra-low latency at Layer 4.
Show answer and explanation
Correct answers: A, B, E
Explanation
AWS offers different types of load balancers tailored for specific use cases. The Application Load Balancer operates at Layer 7, providing advanced routing based on application-level data (e.g., HTTP headers, URLs). On the other hand, the Network Load Balancer operates at Layer 4, routing traffic based on IP and port information with high throughput and low latency. Understanding the OSI layer at which each load balancer operates is essential for designing scalable and efficient architectures in AWS.
- A. Correct.
Correct: The Application Load Balancer (ALB) operates at Layer 7 (Application Layer) of the OSI model, enabling advanced routing features such as content-based routing based on HTTP headers, URLs, and query strings.
- B. Correct.
Correct: The Network Load Balancer (NLB) operates at Layer 4 (Transport Layer) of the OSI model, routing traffic based on IP addresses and TCP/UDP ports. It is optimized for high performance and low latency.
- C. Incorrect.
Incorrect: The Application Load Balancer does not operate at Layer 3 (Network Layer). It specifically operates at Layer 7, focusing on application-level routing functionalities.
- D. Incorrect.
Incorrect: The Network Load Balancer does not operate at Layer 7. It works at Layer 4, handling transport-level traffic based on IP and port information, not application-level content.
- E. Correct.
Correct: The Network Load Balancer is designed to handle millions of requests per second with ultra-low latency, making it ideal for high-performance workloads at Layer 4.