Health checks in HLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary purpose of health checks in a distributed system?

Health checks are used in distributed systems to monitor the status of components. What is their main goal?

A To increase the storage capacity of the system

B To verify if components are alive and responsive to requests

C To encrypt data between services

D To balance the load evenly across all servers

💡 Hint

Think about what 'health' means for a service in a system.

Health checks help detect if a component is alive and can respond, enabling the system to avoid sending requests to failed parts.

❓ Architecture

intermediate

Which health check type is best for detecting if a web service can handle requests properly?

There are different health check types: TCP, HTTP, and custom application-level checks. Which one best confirms a web service is fully operational?

A HTTP health check that requests a specific endpoint returning status 200

B TCP health check to verify the port is open

C Ping the server's IP address

D Check disk space on the server

💡 Hint

Consider which check confirms the service logic is working, not just network availability.

HTTP health checks that call a specific endpoint confirm the service is running and can process requests correctly.

❓ scaling

advanced

How can frequent health checks impact system scalability?

Consider a system with thousands of instances. What is a potential downside of very frequent health checks?

A They reduce the number of instances needed

B They improve system throughput by reducing errors

C They encrypt communication between instances

D They can overload the network and increase latency

💡 Hint

Think about the cost of sending many requests frequently.

Very frequent health checks generate extra network traffic and processing load, which can degrade performance and scalability.

❓ tradeoff

advanced

What is a tradeoff when using aggressive health check timeouts?

Setting very short timeouts for health checks can detect failures quickly but may cause what issue?

A Increased storage requirements for logs

B Longer recovery times after failure

C False positives where healthy services are marked unhealthy

D Reduced network bandwidth usage

💡 Hint

Think about what happens if a service is slow but still healthy.

Short timeouts may cause healthy but slow services to be marked as unhealthy, leading to unnecessary failovers.

❓ component

expert

In a microservices architecture, which component is best suited to aggregate health check results from multiple services?

You have many microservices each with their own health checks. Which component should collect and present a unified health status?

A A centralized health aggregator service that polls each service's health endpoint

B Each service writes health data directly to a shared database without aggregation

C Load balancers perform health checks and store results locally without sharing

D Clients perform health checks on all services individually

💡 Hint

Consider how to get a single view of system health efficiently.

A centralized health aggregator collects health data from all services and provides a unified status, simplifying monitoring and alerting.