Why load balancing distributes traffic in Nginx - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a basic load balancer using NGINX.

Nginx

upstream backend {
    server [1];
}

server {
    listen 80;
    location / {
        proxy_pass http://backend;
    }
}

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

Alocalhost:8080

B192.168.1.1:80

C127.0.0.1:8080

Dexample.com:80

Attempts:

3 left

💡 Hint

Common Mistakes

Using domain names without ports

Using IP without port

Using invalid IP addresses

The server directive inside upstream defines the backend server address. Using 127.0.0.1:8080 is a common local backend example.

2fill in blank

medium

Complete the code to set the load balancing method to round robin.

Nginx

upstream backend {
    # [1];
    server 127.0.0.1:8080;
    server 127.0.0.1:8081;
}

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

Around_robin

Bip_hash

Cleast_conn

Dweight

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'least_conn' or 'ip_hash' which are different methods

Using 'weight' which is not a method directive

The default load balancing method in NGINX is round robin, but explicitly setting round_robin clarifies the method used.

3fill in blank

hard

Fix the error in the load balancer configuration to enable sticky sessions.

Nginx

upstream backend {
    [1];
    server 192.168.0.10;
    server 192.168.0.11;
}

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

Aleast_conn

Bip_hash

Cround_robin

Dsticky

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'sticky' which is not a valid directive in standard NGINX

Using 'round_robin' which does not guarantee sticky sessions

To enable sticky sessions in NGINX, the ip_hash directive is used to route clients to the same server based on their IP.

4fill in blank

hard

Fill both blanks to configure weighted load balancing for two servers.

Nginx

upstream backend {
    server 10.0.0.1 weight=[1];
    server 10.0.0.2 weight=[2];
}

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

A3

B1

C5

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero weight which disables the server

Using equal weights which does not show weighted distribution

Weights control how much traffic each server receives. A weight of 5 sends more traffic than a weight of 1.

5fill in blank

hard

Fill all three blanks to create a health check for backend servers.

Nginx

server {
    listen 80;
    location / {
        proxy_pass http://backend;
        proxy_next_upstream [1];
        proxy_connect_timeout [2]s;
        proxy_read_timeout [3]s;
    }
}

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

Aerror timeout invalid_header

B5

C10

Doff

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'off' disables retries

Using zero or negative timeouts causes errors

proxy_next_upstream defines when to try the next server. Timeouts control connection and read wait times.

Practice

1. Why does Nginx use load balancing to distribute traffic across multiple servers?

easy

A. To increase the size of the server's hard drive

B. To prevent any single server from becoming overloaded and improve response time

C. To reduce the number of servers needed

D. To make the website design look better

Solution

1. Step 1: Understand the purpose of load balancing

   Load balancing spreads incoming requests across multiple servers to avoid overloading one server.

2. Step 2: Recognize the benefit of spreading traffic

   By distributing traffic, servers handle requests faster and the service stays stable.

3. Final Answer:

   To prevent any single server from becoming overloaded and improve response time -> Option B

4. Quick Check:

   Load balancing improves speed and stability [OK]

Hint: Load balancing shares work to keep servers fast and stable [OK]

Common Mistakes:

• Thinking load balancing increases server storage
• Believing it reduces the number of servers needed
• Confusing load balancing with website design

2. Which of the following is the correct syntax to define a load balancing group in Nginx?

easy

A. server_group backend { 192.168.1.10; 192.168.1.11; }

B. loadbalance backend { server 192.168.1.10; server 192.168.1.11; }

C. upstream backend { server 192.168.1.10; server 192.168.1.11; }

D. proxy_pass backend { server 192.168.1.10; server 192.168.1.11; }

Solution

1. Step 1: Identify Nginx load balancing syntax

   Nginx uses the upstream block to define a group of servers for load balancing.

2. Step 2: Check the correct block and server entries

   The correct syntax is upstream backend { server IP; server IP; } to list servers.

3. Final Answer:

   upstream backend { server 192.168.1.10; server 192.168.1.11; } -> Option C

4. Quick Check:

   Use upstream for server groups [OK]

Hint: Remember: 'upstream' defines server groups in Nginx [OK]

Common Mistakes:

• Using 'loadbalance' instead of 'upstream'
• Writing 'server_group' which is invalid
• Misusing 'proxy_pass' inside server group

3. Given this Nginx config snippet, what happens when a client sends a request?

upstream backend {
  server 192.168.1.10;
  server 192.168.1.11;
}
server {
  location / {
    proxy_pass http://backend;
  }
}

medium

A. The request is distributed between 192.168.1.10 and 192.168.1.11

B. The request is sent to only 192.168.1.10 every time

C. The request is blocked because of missing proxy settings

D. The request is sent to 192.168.1.11 only

Solution

1. Step 1: Understand the upstream block

   The upstream backend defines two servers to share traffic.

2. Step 2: Analyze proxy_pass usage

   The proxy_pass http://backend; sends requests to the upstream group, distributing load.

3. Final Answer:

   The request is distributed between 192.168.1.10 and 192.168.1.11 -> Option A

4. Quick Check:

   Requests split across servers [OK]

Hint: proxy_pass to upstream sends requests to all servers [OK]

Common Mistakes:

• Thinking requests always go to first server
• Assuming proxy_pass blocks requests without extra config
• Believing requests go to only one fixed server

4. You configured Nginx load balancing but all traffic goes to one server only. What is the likely cause?

medium

A. The upstream block has only one server listed

B. The load balancing method is set to 'ip_hash'

C. The servers are offline

D. The proxy_pass URL does not match the upstream name

Solution

1. Step 1: Check upstream and proxy_pass names

   If proxy_pass points to a different name than the upstream block, load balancing won't work.

2. Step 2: Understand traffic routing

   Requests will not be distributed if proxy_pass does not reference the correct upstream group.

3. Final Answer:

   The proxy_pass URL does not match the upstream name -> Option D

4. Quick Check:

   proxy_pass must match upstream name [OK]

Hint: proxy_pass name must match upstream block name exactly [OK]

Common Mistakes:

• Ignoring mismatch between proxy_pass and upstream name
• Assuming offline servers cause all traffic to one server
• Confusing load balancing methods with traffic distribution issues

5. You want to ensure Nginx distributes traffic evenly but also keeps a user's requests on the same server. Which load balancing method should you use?

hard

A. ip_hash

B. least_conn

C. random

D. round_robin

Solution

1. Step 1: Understand load balancing methods

   round_robin distributes evenly but does not keep user sessions on one server.

2. Step 2: Identify method that keeps user on same server

   ip_hash uses client IP to send requests to the same server, maintaining session consistency.

3. Final Answer:

   ip_hash -> Option A

4. Quick Check:

   ip_hash keeps user on same server [OK]

Hint: Use ip_hash to stick users to one server [OK]

Common Mistakes:

• Choosing round_robin for session persistence
• Confusing least_conn with user stickiness
• Thinking random method keeps sessions consistent