Teach a load balancer what healthy means — Application Load Balancer and Health checks

Your goal

Choose how often a target group checks an app and read the setting back.

Why this matters

A running server can still have a broken application. Target groups store how often to check an app. You will change the interval and inspect the health-check configuration without inventing a healthy result.

Words you will use

A target group collects app destinations. A health check requests a path to assess a target. A threshold is the number of results needed to change health status.

How to proceed

Start a fresh emulator, read each numbered step, and enter the practice settings shown. Run the action, inspect its API receipt, then continue. Finish lab checks the emulator state again before saving your progress.

1. Create a target group

Create a VPC and an HTTP target group with /health as its check path. A health check asks an app whether it is ready. This group has no running targets, so it cannot prove an app is healthy.

2. Set the check interval

Choose how many seconds to wait between checks. Save that value on the target group. On AWS, failure thresholds also matter, and an all-unhealthy group has special fail-open behavior.

Seconds between checks: Choose 5–300 seconds. This changes the saved check schedule. Suggested practice value: 30.

3. Read the health-check configuration

Describe the target group and compare HealthCheckIntervalSeconds with your input. You have configured a check; you have not run one against a real server.

Practice, then check your understanding

Perform the actions yourself and inspect the returned state. Errors keep your settings so you can retry. Starting another lab clears the previous live environment. Earned XP is kept, and signed-in achievements sync to your account. Replay does not award duplicate XP.

Read the official AWS documentation for service behavior and production details.