Why load balancers distribute traffic in HLD - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to describe the main purpose of a load balancer.

HLD

A load balancer helps to [1] incoming network traffic across multiple servers.

Drag options to blanks, or click blank then click option'

Aignore

Bdistribute

Cblock

Dduplicate

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'block' or 'ignore' which do not describe load balancer behavior.

The main role of a load balancer is to distribute incoming traffic evenly to prevent any single server from being overwhelmed.

2fill in blank

medium

Complete the code to explain why load balancers improve system performance.

HLD

By distributing traffic, load balancers help to [1] server overload and improve response times.

Drag options to blanks, or click blank then click option'

Acause

Bignore

Cprevent

Ddelay

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting 'cause' which is the opposite of the correct meaning.

Load balancers prevent any single server from becoming overloaded, which helps keep response times fast.

3fill in blank

hard

Fix the error in the statement about load balancers.

HLD

Load balancers [1] all traffic to a single server to simplify management.

Drag options to blanks, or click blank then click option'

Adistribute

Bignore

Csend

Dblock

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'send' which implies sending all traffic to one server.

Load balancers distribute traffic across multiple servers, not send all to one server.

4fill in blank

hard

Fill both blanks to complete the explanation of load balancer benefits.

HLD

Load balancers improve [1] by distributing traffic and increase [2] by avoiding server overload.

Drag options to blanks, or click blank then click option'

Aperformance

Bsecurity

Creliability

Dcost

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing security or cost as primary benefits in this context.

Load balancers improve performance and reliability by managing traffic and preventing overload.

5fill in blank

hard

Fill all three blanks to complete the load balancer request flow.

HLD

Client sends request to [1], which [2] the request to a [3] server.

Drag options to blanks, or click blank then click option'

Aload balancer

Broutes

Chealthy

Ddatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'database' instead of 'healthy' server, which is incorrect in this flow.

The client sends a request to the load balancer, which routes it to a healthy server to handle the request.

Practice

1. Why do load balancers distribute incoming traffic across multiple servers?

easy

A. To prevent any single server from becoming overloaded and improve system reliability

B. To increase the number of servers needed for the system

C. To slow down the response time for users

D. To reduce the total number of user requests

Solution

1. Step 1: Understand server overload

   When too many requests go to one server, it slows down or crashes.

2. Step 2: Role of load balancers

   Load balancers spread requests evenly to keep servers healthy and fast.

3. Final Answer:

   To prevent any single server from becoming overloaded and improve system reliability -> Option A

4. Quick Check:

   Load balancers prevent overload = C [OK]

Hint: Load balancers keep servers from getting too busy [OK]

Common Mistakes:

• Thinking load balancers reduce total requests
• Believing load balancers slow down responses
• Assuming load balancers increase server count unnecessarily

2. Which of the following is a common method used by load balancers to distribute traffic?

easy

A. Bubble sort

B. Binary search

C. Depth-first search

D. Round-robin

Solution

1. Step 1: Identify load balancing methods

   Common methods include round-robin and least connections.

2. Step 2: Match options to known methods

   Round-robin cycles through servers evenly; others are unrelated algorithms.

3. Final Answer:

   Round-robin -> Option D

4. Quick Check:

   Round-robin is a load balancing method = D [OK]

Hint: Round-robin cycles requests evenly [OK]

Common Mistakes:

• Confusing sorting/search algorithms with load balancing
• Choosing unrelated computer science terms
• Ignoring common load balancing strategies

3. Consider a load balancer using the least connections strategy. If Server A has 3 active connections and Server B has 1 active connection, where will the next request be sent?

medium

A. Server B

B. Server A

C. Both servers equally

D. To a new server not listed

Solution

1. Step 1: Understand least connections strategy

   It sends new requests to the server with fewer active connections.

2. Step 2: Compare active connections

   Server A has 3, Server B has 1, so Server B has fewer connections.

3. Final Answer:

   Server B -> Option A

4. Quick Check:

   Least connections picks server with fewer connections = B [OK]

Hint: Send to server with least active connections [OK]

Common Mistakes:

• Choosing server with more connections
• Assuming equal distribution regardless of load
• Thinking new servers are automatically chosen

4. A load balancer is configured to use round-robin but always sends requests to the same server. What is the most likely cause?

medium

A. The servers are all down

B. The load balancer is not tracking the last server used correctly

C. The network is too slow

D. The user requests are too few

Solution

1. Step 1: Understand round-robin behavior

   Round-robin cycles through servers in order to balance load.

2. Step 2: Identify cause of repeated server selection

   If it always picks the same server, it likely lost track of which server was last used.

3. Final Answer:

   The load balancer is not tracking the last server used correctly -> Option B

4. Quick Check:

   Round-robin needs correct tracking = A [OK]

Hint: Round-robin must remember last server used [OK]

Common Mistakes:

• Blaming server downtime without checking load balancer
• Assuming network speed affects server choice
• Thinking low request volume causes imbalance

5. You design a system with a load balancer distributing traffic to 5 servers. Suddenly, one server becomes much slower but still receives equal requests. What change to the load balancing strategy can improve overall system performance?

hard

A. Use round-robin but add more user requests

B. Increase the number of servers without changing strategy

C. Switch from round-robin to least connections to avoid slow server overload

D. Disable the load balancer and send requests to one server

Solution

1. Step 1: Identify problem with round-robin

   Round-robin sends equal requests regardless of server speed, causing slow server overload.

2. Step 2: Choose better strategy

   Least connections sends requests to less busy servers, reducing load on slow server.

3. Final Answer:

   Switch from round-robin to least connections to avoid slow server overload -> Option C

4. Quick Check:

   Least connections adapts to server speed = A [OK]

Hint: Use least connections to avoid slow servers [OK]

Common Mistakes:

• Adding servers without fixing load distribution
• Increasing requests worsens overload
• Disabling load balancer causes single point failure