Availability checking in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is availability checking in system design?

Availability checking is the process of verifying if a resource, service, or system component is ready and able to handle requests or tasks at a given time.

beginner

Why is availability checking important in distributed systems?

It ensures that requests are sent only to components that are up and responsive, improving reliability and user experience by avoiding failures or delays.

intermediate

Name two common methods used for availability checking.

1. Heartbeat signals: periodic messages to confirm a component is alive.<br>2. Health checks: active tests like ping or API calls to verify responsiveness.

beginner

What is a heartbeat in availability checking?

A heartbeat is a regular signal sent by a system component to indicate it is operational and reachable.

intermediate

How does availability checking help in load balancing?

Load balancers use availability checks to route traffic only to healthy servers, preventing requests from going to down or overloaded machines.

What does availability checking verify in a system?

A If a component is cost-effective

B If a component has enough storage

C If a component is secure

D If a component is ready to handle requests

Availability checking confirms readiness to handle requests, not storage, security, or cost.

Which method is commonly used for availability checking?

A Data compression

B Encryption

C Heartbeat signals

D Caching

Heartbeat signals are used to confirm if a component is alive and responsive.

How does availability checking improve user experience?

A By avoiding requests to down components

B By increasing data storage

C By reducing network speed

D By encrypting data

It prevents sending requests to unavailable components, reducing errors and delays.

What role does availability checking play in load balancing?

A Increases server storage

B Routes traffic to healthy servers only

C Encrypts server data

D Compresses server responses

Load balancers use availability checks to send traffic only to servers that are up and healthy.

Which of these is NOT a typical availability check?

A User authentication

B Heartbeat signal

C Health check API call

D Ping test

User authentication is unrelated to availability checking.

Explain availability checking and why it is critical in system design.

Think about how systems know if parts are working before sending requests.

Describe how availability checking integrates with load balancing.

Consider how traffic is distributed only to servers that respond well.