Round-robin (default) in Nginx - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the default load balancing method in NGINX?

NGINX uses a load balancing method to distribute client requests across multiple servers. What is the default method used if none is specified?

A Random

B Least connections

C Round-robin

D IP hash

💡 Hint

Think about the simplest way to distribute requests evenly without extra configuration.

The default load balancing method in NGINX is round-robin. It cycles through the servers in order, sending each new request to the next server.

❓ Configuration

intermediate

Identify the correct NGINX upstream block for round-robin load balancing

Which of the following NGINX upstream configurations correctly sets up round-robin load balancing for two backend servers?

A

upstream backend {
    server backend1.example.com;
    server backend2.example.com;
}

B

upstream backend {
    least_conn;
    server backend1.example.com;
    server backend2.example.com;
}

C

upstream backend {
    ip_hash;
    server backend1.example.com;
    server backend2.example.com;
}

D

upstream backend {
    random;
    server backend1.example.com;
    server backend2.example.com;
}

💡 Hint

Round-robin is the default and requires no extra directive inside the upstream block.

In NGINX, round-robin is the default load balancing method. You just list the servers inside the upstream block without any extra keywords.

❓ Troubleshoot

advanced

Why might NGINX not distribute requests evenly in round-robin mode?

You configured NGINX with multiple backend servers using round-robin. However, one server receives significantly more requests than others. What could cause this behavior?

A One backend server is slower and NGINX retries requests on it more often.

B Round-robin requires explicit configuration; without it, NGINX uses least connections.

C NGINX caches DNS and resolves backend IPs only once, causing uneven distribution if IPs change.

D Client connections are kept alive and reused, so requests stick to the same backend server.

💡 Hint

Think about how persistent connections affect request distribution.

NGINX uses persistent connections by default. If clients reuse connections, requests go to the same backend server, causing uneven load despite round-robin.

✅ Best Practice

advanced

What is a recommended practice when using round-robin load balancing in NGINX?

When using round-robin load balancing in NGINX, which practice helps ensure better distribution and reliability?

A Enable health checks to remove unhealthy backend servers automatically.

B Use IP hash to guarantee the same client always hits the same server.

C Disable keepalive connections to force new connections for each request.

D Configure random load balancing to avoid predictable server selection.

💡 Hint

Think about how to avoid sending requests to servers that are down.

Health checks help NGINX detect and exclude unhealthy backend servers, improving reliability when using round-robin.

🧠 Conceptual

expert

How does NGINX implement round-robin load balancing internally?

Which statement best describes how NGINX distributes requests using round-robin load balancing by default?

A NGINX selects the backend server with the fewest active connections for each new request.

B NGINX cycles through the list of backend servers sequentially, sending each new request to the next server in order.

C NGINX hashes the client IP address to consistently route requests from the same client to the same server.

D NGINX randomly selects a backend server for each request to distribute load unpredictably.

💡 Hint

Round-robin means taking turns in a fixed order.

Round-robin load balancing means NGINX sends requests one by one to each backend server in the order they are listed, cycling back to the first after the last.