API API Performance Testing 1 — Questions and Answers
Question 1: Which tool is most commonly used for API load and performance testing?
- Postman
- JMeter (Correct answer)
- Swagger
- Insomnia
Correct answer: JMeter
Apache JMeter is the most widely adopted open-source tool for load testing APIs by simulating concurrent users.
Question 2: What is the goal of load testing an API?
- Find security vulnerabilities
- Evaluate API behavior under expected peak traffic (Correct answer)
- Validate JSON schema
- Test authentication flows
Correct answer: Evaluate API behavior under expected peak traffic
Load testing simulates expected production traffic levels to ensure the API meets performance requirements under real-world conditions.
Question 3: What does 'throughput' measure in API performance testing?
- Average response size
- Number of requests processed per unit of time (Correct answer)
- Error rate percentage
- Memory usage on the server
Correct answer: Number of requests processed per unit of time
Throughput measures how many API requests a system can successfully handle per second or minute, indicating capacity.
Question 4: What type of performance test pushes the API beyond its capacity to find the breaking point?
- Load test
- Smoke test
- Stress test (Correct answer)
- Soak test
Correct answer: Stress test
Stress testing deliberately overloads the API beyond its designed capacity to identify failure modes and recovery behavior.
Question 5: What is a 'soak test' (endurance test) in API performance testing?
- A test with extremely high traffic spikes
- A test that runs at normal load for an extended period to detect memory leaks (Correct answer)
- A test that checks API responses for correctness
- A test with zero load to measure baseline
Correct answer: A test that runs at normal load for an extended period to detect memory leaks
Soak testing (endurance testing) runs the API at sustained normal load for hours or days to detect degradation, memory leaks, and resource exhaustion.
Question 6: What does P99 latency mean in API performance metrics?
- The average response time
- The response time at which 99% of requests complete faster (Correct answer)
- The maximum response time recorded
- The error rate at 99% load
Correct answer: The response time at which 99% of requests complete faster
P99 (99th percentile latency) means 99% of API requests complete within this time, capturing near-worst-case user experience.
API API Performance Testing 1
Which tool is most commonly used for API load and performance testing?