Why load balancing matters in AWS - Quick Recap

Recall & Review

beginner

What is load balancing in cloud infrastructure?

Load balancing is the process of distributing incoming network traffic across multiple servers to ensure no single server is overwhelmed, improving performance and reliability.

beginner

Why does load balancing improve application availability?

Because it spreads traffic across servers, if one server fails, others can handle the load, keeping the application running smoothly without interruption.

intermediate

How does load balancing help with scaling applications?

Load balancing allows adding or removing servers easily to handle more or less traffic, helping applications grow or shrink without downtime.

beginner

What is a real-life example of load balancing?

Imagine a busy restaurant where a host seats guests evenly among several waiters so no waiter is overwhelmed and all guests get good service quickly.

beginner

What AWS service is commonly used for load balancing?

AWS Elastic Load Balancing (ELB) automatically distributes incoming application traffic across multiple targets like EC2 instances.

What is the main purpose of load balancing?

A Create backups automatically

B Store data securely

C Distribute traffic evenly across servers

D Monitor server health only

Load balancing distributes incoming traffic evenly to prevent any server from being overloaded.

How does load balancing improve fault tolerance?

A By routing traffic away from failed servers

B By shutting down servers during peak times

C By increasing server storage capacity

D By encrypting all data

Load balancers detect failed servers and stop sending traffic to them, keeping the system running.

Which AWS service provides load balancing?

A Amazon S3

B Elastic Load Balancer (ELB)

C Amazon RDS

D AWS Lambda

Elastic Load Balancer (ELB) is the AWS service designed for load balancing.

Load balancing helps applications to:

A Scale smoothly with traffic changes

B Reduce data storage costs

C Encrypt user data

D Create user accounts

Load balancing allows applications to handle more or less traffic by distributing requests efficiently.

What happens if there is no load balancing and one server gets too much traffic?

A Traffic will be evenly shared anyway

B The server will automatically upgrade hardware

C The server will send traffic to other servers

D The server may slow down or crash

Without load balancing, a single server can become overwhelmed, causing slowdowns or crashes.

Explain why load balancing is important for cloud applications.

Think about how spreading work helps keep things running smoothly.

Describe how AWS Elastic Load Balancer helps manage traffic.

Focus on how ELB keeps traffic flowing to healthy servers.

Practice

1. What is the main purpose of a load balancer in AWS?

easy

A. To create backups of servers automatically

B. To store user data securely

C. To distribute incoming traffic evenly across multiple servers

D. To monitor server CPU usage only

Solution

1. Step 1: Understand load balancer role

   A load balancer shares user traffic across servers to keep apps fast and reliable.

2. Step 2: Identify main function

   Its main job is to distribute incoming traffic evenly to avoid overloading one server.

3. Final Answer:

   To distribute incoming traffic evenly across multiple servers -> Option C

4. Quick Check:

   Load balancer = distribute traffic [OK]

Hint: Load balancer spreads traffic to avoid overload [OK]

Common Mistakes:

• Confusing load balancer with data storage
• Thinking it only monitors CPU
• Assuming it creates backups

2. Which AWS service is used to create a load balancer?

easy

A. Amazon S3

B. Elastic Load Balancing (ELB)

C. Amazon RDS

D. AWS Lambda

Solution

1. Step 1: Identify AWS services

   Amazon S3 stores files, RDS manages databases, Lambda runs code, ELB manages load balancing.

2. Step 2: Match service to load balancing

   Elastic Load Balancing (ELB) is the AWS service designed to create load balancers.

3. Final Answer:

   Elastic Load Balancing (ELB) -> Option B

4. Quick Check:

   Load balancer service = ELB [OK]

Hint: ELB is the AWS load balancer service name [OK]

Common Mistakes:

• Choosing storage or compute services instead of ELB
• Confusing Lambda with load balancing
• Selecting database services

3. Given this AWS setup code snippet, what does the load balancer do?

LoadBalancer -> TargetGroup -> EC2 Instances
Listener listens on port 80 and forwards to TargetGroup

medium

A. It forwards traffic on port 80 to all EC2 instances evenly

B. It blocks traffic on port 80

C. It stores data from EC2 instances

D. It only forwards traffic to one EC2 instance

Solution

1. Step 1: Understand listener role

   The listener listens on port 80 and forwards requests to the target group.

2. Step 2: Understand target group role

   The target group contains multiple EC2 instances and the load balancer distributes traffic evenly among them.

3. Final Answer:

   It forwards traffic on port 80 to all EC2 instances evenly -> Option A

4. Quick Check:

   Listener + TargetGroup = distribute traffic [OK]

Hint: Listener forwards traffic evenly to all targets [OK]

Common Mistakes:

• Thinking it blocks traffic
• Assuming it stores data
• Believing it sends traffic to only one instance

4. You set up a load balancer but all traffic goes to a single server. What is the likely mistake?

medium

A. Security group blocks all traffic

B. Listener is set to forward on wrong port

C. Load balancer is not created

D. Target group has only one instance registered

Solution

1. Step 1: Check target group configuration

   If only one instance is registered in the target group, all traffic goes to that instance.

2. Step 2: Verify listener and load balancer existence

   Listener forwarding on wrong port or missing load balancer would cause no traffic or errors, not single server traffic.

3. Final Answer:

   Target group has only one instance registered -> Option D

4. Quick Check:

   Single server traffic = one target instance [OK]

Hint: Check target group instance count first [OK]

Common Mistakes:

• Assuming listener port causes single server traffic
• Thinking load balancer absence sends traffic
• Blaming security group for traffic routing

5. You want to handle sudden traffic spikes without slowing your app. Which load balancing setup helps best?

hard

A. Use a load balancer with multiple target groups and auto-scaling EC2 instances

B. Use a single EC2 instance behind a load balancer

C. Use only one target group with fixed number of instances

D. Disable load balancer and rely on DNS round robin

Solution

1. Step 1: Understand traffic spike handling

   Handling spikes requires scaling resources automatically to meet demand.

2. Step 2: Match setup to scaling needs

   Using a load balancer with multiple target groups and auto-scaling EC2 instances allows dynamic resource adjustment and balanced traffic.

3. Final Answer:

   Use a load balancer with multiple target groups and auto-scaling EC2 instances -> Option A

4. Quick Check:

   Auto-scaling + load balancer = handle spikes [OK]

Hint: Combine load balancer with auto-scaling for spikes [OK]

Common Mistakes:

• Relying on single instance for heavy traffic
• Using fixed instances without scaling
• Disabling load balancer reduces reliability