ALB vs NLB decision in AWS - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Choosing Load Balancer for HTTP Traffic with Advanced Routing

You have a web application that requires routing requests based on URL paths and host headers. Which load balancer type is best suited for this?

A Network Load Balancer (NLB) because it handles TCP traffic efficiently.

B Gateway Load Balancer because it is designed for third-party virtual appliances.

C Classic Load Balancer because it supports both HTTP and TCP protocols.

D Application Load Balancer (ALB) because it supports path-based and host-based routing.

💡 Hint

Think about which load balancer can inspect HTTP headers to route traffic.

ALB operates at the application layer and supports advanced routing like path and host-based rules, making it ideal for HTTP traffic that requires such routing.

❓ service_behavior

intermediate

Load Balancer Choice for High Throughput TCP Traffic

Your application requires handling millions of TCP connections with very low latency. Which load balancer should you choose?

A Network Load Balancer (NLB) because it operates at the connection level and handles millions of connections efficiently.

B Application Load Balancer (ALB) because it supports HTTP/2 and WebSocket.

C Classic Load Balancer because it supports both HTTP and TCP protocols.

D Gateway Load Balancer because it is optimized for third-party appliances.

💡 Hint

Consider which load balancer works best at the transport layer for TCP traffic.

NLB works at the transport layer (Layer 4) and is designed to handle millions of TCP connections with low latency, making it suitable for high throughput TCP workloads.

❓ Architecture

advanced

Designing a Highly Available Web Application with SSL Termination

You want to design a highly available web application that terminates SSL connections at the load balancer and supports sticky sessions. Which load balancer type should you use?

A Classic Load Balancer because it does not support SSL termination.

B Application Load Balancer (ALB) because it supports SSL termination and sticky sessions at the application layer.

C Network Load Balancer (NLB) because it supports SSL termination and sticky sessions.

D Gateway Load Balancer because it is designed for routing traffic to virtual appliances.

💡 Hint

Think about which load balancer can handle SSL termination and session stickiness at the application layer.

ALB supports SSL termination and sticky sessions (session affinity) at the application layer, which is essential for web applications requiring these features.

❓ security

advanced

Load Balancer Choice for Protecting Against DDoS Attacks on TCP Ports

Your application needs protection against DDoS attacks on TCP ports and requires static IP addresses for firewall whitelisting. Which load balancer fits these requirements?

A Classic Load Balancer because it supports static IP addresses.

B Application Load Balancer (ALB) because it provides static IP addresses and DDoS protection.

C Network Load Balancer (NLB) because it provides static IP addresses and integrates with AWS Shield for DDoS protection.

D Gateway Load Balancer because it is designed for third-party firewall appliances.

💡 Hint

Consider which load balancer provides static IPs and integrates with AWS Shield.

NLB provides static IP addresses and integrates with AWS Shield for DDoS protection, making it suitable for TCP port protection and firewall whitelisting.

✅ Best Practice

expert

Optimizing Cost and Performance for Mixed HTTP and TCP Workloads

You have a mixed workload: HTTP traffic requiring advanced routing and TCP traffic requiring high throughput. You want to optimize cost and performance. What is the best architecture?

A Use a Network Load Balancer (NLB) for TCP traffic and an Application Load Balancer (ALB) for HTTP traffic to optimize performance and cost.

B Use two Network Load Balancers (NLBs), one for HTTP and one for TCP traffic, to maximize throughput.

C Use a single Application Load Balancer (ALB) for both HTTP and TCP traffic to reduce cost.

D Use a Classic Load Balancer to handle both HTTP and TCP traffic in one place.

💡 Hint

Think about which load balancer is best for each protocol and how to combine them efficiently.

Using NLB for TCP traffic and ALB for HTTP traffic allows each load balancer to handle the traffic type it is optimized for, balancing cost and performance effectively.

Practice

1. Which AWS load balancer should you choose if you want to route HTTP requests based on URL paths?

easy

A. Gateway Load Balancer

B. Network Load Balancer (NLB)

C. Classic Load Balancer

D. Application Load Balancer (ALB)

Solution

1. Step 1: Understand ALB routing capabilities

   ALB can route HTTP/HTTPS traffic based on content like URL paths or host headers.

2. Step 2: Compare with NLB capabilities

   NLB routes at the network level and does not inspect HTTP content for routing.

3. Final Answer:

   Application Load Balancer (ALB) -> Option D

4. Quick Check:

   Content-based routing = ALB [OK]

Hint: Use ALB for HTTP content routing, not NLB [OK]

Common Mistakes:

• Choosing NLB for HTTP content routing
• Confusing Classic Load Balancer with ALB
• Assuming NLB can inspect HTTP headers

2. Which protocol is primarily supported by Network Load Balancer (NLB) for fast, low-latency traffic?

easy

A. TCP/UDP

B. FTP

C. HTTP/HTTPS

D. SMTP

Solution

1. Step 1: Identify NLB protocol support

   NLB is designed to handle TCP and UDP traffic for fast, low-latency connections.

2. Step 2: Exclude HTTP/HTTPS protocols

   HTTP/HTTPS are application layer protocols handled by ALB, not NLB.

3. Final Answer:

   TCP/UDP -> Option A

4. Quick Check:

   NLB = TCP/UDP traffic [OK]

Hint: NLB handles TCP/UDP, ALB handles HTTP/HTTPS [OK]

Common Mistakes:

• Selecting HTTP/HTTPS for NLB
• Confusing FTP or SMTP as NLB protocols
• Assuming NLB supports application layer protocols

3. You have a web application that requires routing requests based on hostnames and needs SSL termination. Which load balancer will correctly handle this?

medium

A. Network Load Balancer (NLB)

B. Gateway Load Balancer

C. Application Load Balancer (ALB)

D. Classic Load Balancer

Solution

1. Step 1: Check hostname-based routing support

   ALB supports routing based on hostnames, which is needed here.

2. Step 2: Confirm SSL termination capability

   ALB can terminate SSL connections, simplifying certificate management.

3. Final Answer:

   Application Load Balancer (ALB) -> Option C

4. Quick Check:

   Hostname routing + SSL termination = ALB [OK]

Hint: SSL termination and hostname routing need ALB [OK]

Common Mistakes:

• Choosing NLB which lacks hostname routing
• Assuming Classic Load Balancer supports advanced routing
• Confusing Gateway Load Balancer with ALB

4. A developer configured a Network Load Balancer to route HTTP traffic and expects it to inspect URL paths for routing. Why is this setup incorrect?

medium

A. NLB does not support TCP traffic

B. NLB cannot inspect HTTP content for routing decisions

C. NLB requires SSL certificates for HTTP routing

D. NLB only supports routing based on IP addresses

Solution

1. Step 1: Understand NLB routing capabilities

   NLB operates at the network layer and cannot inspect HTTP content like URL paths.

2. Step 2: Identify why HTTP content inspection fails

   Routing based on URL paths requires application layer inspection, which only ALB supports.

3. Final Answer:

   NLB cannot inspect HTTP content for routing decisions -> Option B

4. Quick Check:

   NLB lacks HTTP content inspection [OK]

Hint: NLB works at network layer, no HTTP content routing [OK]

Common Mistakes:

• Thinking NLB supports HTTP path routing
• Confusing TCP support with HTTP inspection
• Assuming SSL certs fix routing issues

5. You need to design a system that handles millions of TCP connections with very low latency and also routes HTTP requests based on URL paths. What is the best load balancer setup?

hard

A. Use NLB for TCP connections and ALB for HTTP routing

B. Use only an Application Load Balancer (ALB) for all traffic

C. Use only a Network Load Balancer (NLB) for all traffic

D. Use Classic Load Balancer for both TCP and HTTP traffic

Solution

1. Step 1: Identify requirements for TCP and HTTP traffic

   Millions of TCP connections need low latency, best handled by NLB. HTTP routing by URL paths requires ALB.

2. Step 2: Combine load balancers for best performance

   Use NLB for TCP traffic and ALB for HTTP traffic to meet both needs efficiently.

3. Final Answer:

   Use NLB for TCP connections and ALB for HTTP routing -> Option A

4. Quick Check:

   TCP low latency + HTTP routing = NLB + ALB [OK]

Hint: Combine NLB for TCP and ALB for HTTP routing [OK]

Common Mistakes:

• Using only ALB for TCP traffic causing latency
• Using only NLB missing HTTP routing features
• Choosing Classic Load Balancer for modern needs