API monitoring and alerting in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this curl command?

You run this command to check an API endpoint status:

curl -s -o /dev/null -w "%{http_code}" https://api.example.com/status

What output will this command produce if the API is healthy?

Rest API

curl -s -o /dev/null -w "%{http_code}" https://api.example.com/status

A 500

B OK

C 404

D 200

💡 Hint

The command outputs the HTTP status code only.

The curl command with -w "%{http_code}" prints the HTTP status code. 200 means success.

🧠 Conceptual

intermediate

Which alert condition best detects API downtime?

You want to create an alert for your API monitoring tool. Which condition below best detects when the API is down?

A Alert if HTTP status code is 500 or 503

B Alert if response time > 1 second

C Alert if API returns any 2xx status code

D Alert if API response body contains 'success'

💡 Hint

Server errors indicate downtime or failure.

HTTP 500 and 503 status codes indicate server errors or service unavailable, signaling downtime.

❓ Configuration

advanced

Which Prometheus alert rule triggers on high API error rate?

Given this Prometheus metric: api_request_errors_total counts API errors, and api_requests_total counts total requests.
Which alert rule triggers if error rate exceeds 5% over 5 minutes?

A

alert: HighApiErrors
expr: (rate(api_request_errors_total[5m]) / rate(api_requests_total[5m])) > 0.05
for: 5m

B

alert: HighApiErrors
expr: rate(api_request_errors_total[5m]) > 0.05
for: 5m

C

alert: HighApiErrors
expr: api_request_errors_total / api_requests_total > 0.05
for: 5m

D

alert: HighApiErrors
expr: sum(api_request_errors_total) > 5
for: 5m

💡 Hint

Use rate() to calculate per-second increase over time.

Option A calculates the error rate as the ratio of error requests to total requests over 5 minutes using rate(), then triggers if above 5%.

❓ Troubleshoot

advanced

Why does this alert never trigger?

You configured an alert:

alert: ApiDown
expr: up{job="api"} == 0
for: 10m

But it never triggers even when the API is down. What is the likely cause?

A The expression should use '!=' instead of '=='

B The 'for' duration is too short to trigger

C The 'up' metric is missing or not scraped for the API job

D The alert name must be lowercase

💡 Hint

Check if the metric used in expr is available.

If the 'up' metric is not scraped for the API job, the expression never evaluates to true, so alert never fires.

🔀 Workflow

expert

Order the steps to set up API monitoring with alerting

Arrange these steps in the correct order to set up API monitoring and alerting:

A 2,1,3,4

B 1,2,3,4

C 1,3,2,4

D 3,1,2,4

💡 Hint

Think about defining what to measure before collecting data.

First define what to measure, then collect data, then create alerts, finally test them.