ALB vs NLB decision in AWS - Hands-On Comparison

ALB vs NLB Decision

📖 Scenario: You are working as a cloud architect for a company that needs to set up load balancing for their web applications. They want to understand when to use an Application Load Balancer (ALB) versus a Network Load Balancer (NLB) in AWS.Your task is to create a simple decision helper in Python that helps decide which load balancer to use based on the application requirements.

🎯 Goal: Build a Python script that stores application requirements and uses simple logic to decide whether to use an ALB or NLB.

📋 What You'll Learn

Create a dictionary with application requirements

Add a configuration variable for traffic type

Write logic to decide ALB or NLB based on traffic type

Output the final decision as a variable

💡 Why This Matters

🌍 Real World

Choosing the right AWS load balancer is important for application performance and cost optimization.

💼 Career

Cloud architects and engineers often need to decide between ALB and NLB based on application needs.

1

Create application requirements dictionary

Create a dictionary called app_requirements with these exact entries: 'protocol': 'HTTP', 'port': 80, 'target_type': 'instance'

AWS

# Your code here

Hint

Use curly braces to create a dictionary with keys and values exactly as shown.

2

Add traffic type configuration

Add a variable called traffic_type and set it to the string 'HTTP'

AWS

app_requirements = {'protocol': 'HTTP', 'port': 80, 'target_type': 'instance'}
# Your code here

Hint

Assign the string 'HTTP' to the variable traffic_type.

3

Write decision logic for load balancer

Write an if statement that sets a variable load_balancer_choice to 'ALB' if traffic_type is 'HTTP', otherwise set it to 'NLB'

AWS

app_requirements = {'protocol': 'HTTP', 'port': 80, 'target_type': 'instance'}
traffic_type = 'HTTP'
# Your code here

Hint

Use an if-else statement to assign the correct load balancer choice based on traffic_type.

4

Set final decision variable

Add a variable called final_decision and set it equal to load_balancer_choice

AWS

app_requirements = {'protocol': 'HTTP', 'port': 80, 'target_type': 'instance'}
traffic_type = 'HTTP'
if traffic_type == 'HTTP':
    load_balancer_choice = 'ALB'
else:
    load_balancer_choice = 'NLB'
# Your code here

Hint

Assign the variable final_decision to the value of load_balancer_choice.

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