CDN caching for static content in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of a CDN in caching static content?

A CDN (Content Delivery Network) caches static content close to users to reduce latency and server load, improving load times and user experience.

intermediate

Explain the concept of cache invalidation in CDN caching.

Cache invalidation is the process of updating or removing cached content in the CDN when the original content changes, ensuring users get fresh data.

beginner

What role do TTL (Time To Live) values play in CDN caching?

TTL defines how long cached content stays in the CDN before it expires and must be refreshed from the origin server.

intermediate

Why is it important to separate static and dynamic content in CDN caching?

Static content is cacheable and served quickly from CDN, while dynamic content changes often and usually bypasses CDN to ensure accuracy.

intermediate

How does CDN caching improve scalability of a web application?

By offloading static content delivery to distributed CDN servers, the origin server handles fewer requests, allowing the system to serve more users efficiently.

What type of content is best suited for CDN caching?

A Database queries

B Static content like images and CSS files

C Real-time chat messages

D User-specific dynamic pages

Static content does not change often and can be cached to improve load times.

What happens when cached content's TTL expires in a CDN?

A Content is refreshed from the origin server

B Content is deleted permanently

C Content is served from cache indefinitely

D CDN shuts down

After TTL expires, CDN fetches fresh content from the origin to keep data up to date.

Which method helps ensure users get updated content after a change?

A Cache invalidation

B Increasing TTL

C Ignoring cache

D Using only dynamic content

Cache invalidation updates or removes stale cached content.

How does CDN caching reduce load on the origin server?

A By running database queries

B By blocking user requests

C By storing user data

D By serving cached static content from edge servers

CDN edge servers serve cached content, reducing requests to the origin.

Which of these is NOT a benefit of CDN caching?

A Lower latency for users

B Improved server scalability

C Automatic content creation

D Reduced bandwidth costs

CDNs cache existing content; they do not create content.

Describe how CDN caching works for static content and why it improves user experience.

Think about how content travels from server to user.

Explain the importance of cache invalidation and TTL in maintaining content freshness in CDN caching.

Consider what happens when content changes.