ALB vs NLB decision in AWS - Quick Revision & Key Differences

Recall & Review

beginner

What does ALB stand for and what is its primary use?

ALB stands for Application Load Balancer. It is mainly used to route HTTP and HTTPS traffic based on advanced rules like URL paths or host headers.

beginner

What does NLB stand for and what is its primary use?

NLB stands for Network Load Balancer. It is designed to handle TCP, UDP, and TLS traffic at very high performance and low latency, often for non-HTTP protocols.

beginner

Which load balancer should you choose if you need to route traffic based on URL paths?

Choose ALB because it supports routing decisions based on URL paths and host headers, which NLB does not support.

intermediate

Which load balancer is better for handling millions of requests per second with ultra-low latency?

NLB is better for very high performance and low latency at the network level, making it suitable for millions of requests per second.

beginner

Can ALB handle TCP or UDP traffic?

No, ALB only handles HTTP and HTTPS traffic. For TCP, UDP, or TLS traffic, NLB is the appropriate choice.

Which load balancer supports routing based on HTTP headers?

A Network Load Balancer (NLB)

B Application Load Balancer (ALB)

C Classic Load Balancer

D Gateway Load Balancer

ALB supports routing based on HTTP headers, paths, and hostnames.

Which load balancer is best for handling TCP traffic with very low latency?

A Application Load Balancer (ALB)

B Classic Load Balancer

C Network Load Balancer (NLB)

D Elastic Load Balancer (ELB)

NLB is designed for TCP and UDP traffic with ultra-low latency.

If you need to route HTTPS traffic based on URL path, which load balancer should you use?

A Application Load Balancer

B Classic Load Balancer

C Network Load Balancer

D Gateway Load Balancer

ALB supports advanced routing rules like URL path-based routing.

Which load balancer can handle millions of requests per second efficiently?

A Network Load Balancer

B None of the above

C Classic Load Balancer

D Application Load Balancer

NLB is optimized for very high throughput and low latency.

Which load balancer does NOT support UDP traffic?

A Gateway Load Balancer

B Network Load Balancer

C Classic Load Balancer

D Application Load Balancer

ALB supports only HTTP and HTTPS, not UDP.

Explain when you would choose an Application Load Balancer over a Network Load Balancer.

Think about web applications and how they route user requests.

Describe scenarios where a Network Load Balancer is the better choice.

Consider applications like gaming servers or IoT devices.

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