Network Load Balancer (NLB) in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How does a Network Load Balancer handle sudden traffic spikes?

Imagine a popular online store uses a Network Load Balancer (NLB) to distribute incoming customer requests. Suddenly, a flash sale causes a huge spike in traffic. How does the NLB manage this sudden increase?

A It automatically scales to handle millions of requests per second without pre-warming.

B It queues incoming requests until backend servers are free to handle them.

C It drops excess requests when traffic exceeds a fixed limit set during setup.

D It redirects traffic to a backup load balancer to share the load.

💡 Hint

Think about how NLBs are designed to handle large volumes of traffic efficiently.

Network Load Balancers are built to scale automatically and handle millions of requests per second without needing manual intervention or pre-warming. They do not queue or drop requests but distribute them efficiently.

❓ Architecture

intermediate

Choosing the right target type for an NLB

You are designing a system using an AWS Network Load Balancer. You have two options for targets: IP addresses or instance IDs. Which choice allows you to load balance traffic to resources outside your VPC?

A Using instance IDs because they allow cross-region load balancing.

B Using instance IDs because they represent EC2 instances inside the VPC only.

C Using IP addresses because they can point to any reachable resource, including outside the VPC.

D Using IP addresses because instance IDs are deprecated.

💡 Hint

Consider which target type can represent resources outside the AWS environment.

IP address targets allow the NLB to route traffic to any IP, including on-premises servers or resources outside the VPC. Instance IDs only represent EC2 instances inside the VPC.

❓ scaling

advanced

Estimating capacity for a Network Load Balancer

Your application expects 10 million TCP connections per minute. You plan to use an NLB to distribute this load. Which of the following is the best estimate of the NLB's capacity to handle this traffic?

A NLB can handle up to 1 million connections per minute, so you need 10 NLBs.

B NLB cannot handle TCP connections, only HTTP/HTTPS.

C NLB capacity depends on backend instances, so you must scale instances, not the NLB.

D NLB can handle millions of connections per second, so a single NLB can handle 10 million per minute easily.

💡 Hint

Recall the NLB's design for high throughput and connection handling.

Network Load Balancers are designed to handle millions of connections per second, so 10 million connections per minute is well within a single NLB's capacity.

❓ tradeoff

advanced

Tradeoffs between Network Load Balancer and Application Load Balancer

You need to choose between an AWS Network Load Balancer (NLB) and an Application Load Balancer (ALB) for your service. Which statement correctly describes a key tradeoff?

A NLB operates at the transport layer (TCP/UDP) and offers ultra-low latency, while ALB operates at the application layer (HTTP/HTTPS) with more routing features.

B ALB can handle millions of connections per second, but NLB is limited to thousands.

C NLB supports advanced HTTP routing features, while ALB only supports TCP routing.

D NLB is cheaper but less reliable than ALB.

💡 Hint

Think about the OSI layers where each load balancer operates and their feature sets.

NLB works at the transport layer and is optimized for high performance and low latency TCP/UDP traffic. ALB works at the application layer and supports advanced HTTP routing but with slightly higher latency.

❓ component

expert

Request flow through a Network Load Balancer with multiple AZs

Consider an NLB deployed across three Availability Zones (AZs) with backend instances in each AZ. A client sends a TCP request. Which sequence best describes the request flow from client to backend instance?

A 1, 2, 4, 3

B 1, 2, 3, 4

C 2, 1, 3, 4

D 1, 3, 2, 4

💡 Hint

Think about how NLB preserves client IP and routes within AZs.

The client sends the request to the NLB's static IP. The NLB routes the request to a healthy backend instance in the same AZ to reduce latency. The backend processes and sends the response back through the NLB, which forwards it to the client.