Backup servers in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a backup server in the context of nginx?

A backup server is a secondary server that nginx uses only if the primary server is unavailable or fails. It helps keep the website or service running smoothly.

beginner

How do you define a backup server in an nginx upstream block?

You add the keyword backup after the server address inside the upstream block. For example: <br>

upstream backend {
  server primary.example.com;
  server backup.example.com backup;
}

intermediate

Why use a backup server instead of just multiple primary servers?

A backup server is only used when all primary servers fail. This saves resources and avoids unnecessary load on the backup. It acts like a safety net.

intermediate

What happens if the primary server recovers after the backup server starts handling requests?

nginx automatically switches back to the primary server once it is healthy again, stopping requests to the backup server.

beginner

Write a simple nginx upstream block with one primary and one backup server.

upstream backend {
  server primary.example.com;
  server backup.example.com backup;
}

In nginx, what keyword marks a server as a backup in an upstream block?

A backup

B secondary

C failover

D reserve

The keyword backup is used to mark a server as a backup in nginx upstream configuration.

When does nginx send traffic to a backup server?

A All the time, in rotation

B Only when all primary servers are down

C Only during peak hours

D When the backup server is manually enabled

nginx uses the backup server only if all primary servers are unavailable.

What happens if the primary server comes back online after nginx switched to the backup?

A nginx continues using the backup server forever

B nginx requires a manual restart

C nginx switches back to the primary server automatically

D nginx sends traffic to both servers equally

nginx automatically switches back to the primary server once it is healthy again.

Which of these is NOT a benefit of using a backup server in nginx?

A Reduces load on primary servers during normal operation

B Acts as a safety net for failover

C Improves availability during primary server failure

D Ensures continuous service

Backup servers are idle during normal operation, so they do not reduce load on primary servers.

How do you test if your nginx backup server configuration works?

A Change the backup server to primary

B Restart nginx without changing config

C Add more primary servers

D Stop the primary server and check if requests go to the backup

Stopping the primary server simulates failure and tests if nginx routes traffic to the backup server.

Explain how nginx uses backup servers in load balancing and why they are important.

Think about what happens when the main server is down.

Describe how to configure a backup server in nginx and how nginx switches between primary and backup servers.

Focus on the nginx configuration syntax and behavior.