Purging CDN cache in Azure - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is CDN cache purging?

CDN cache purging is the process of removing stored content from the CDN servers so that fresh content is fetched from the origin server on the next request.

beginner

Why do we need to purge CDN cache?

We purge CDN cache to update or remove outdated or incorrect content so users get the latest version without waiting for cache expiration.

intermediate

Name two common methods to purge CDN cache in Azure.

1. Purge by content path (specific files or folders). 2. Purge everything (clear all cached content).

intermediate

What is the difference between 'purge' and 'invalidate' in CDN cache management?

'Purge' removes cached content immediately, forcing a fresh fetch. 'Invalidate' marks content as stale but may serve old content until refreshed.

advanced

How does purging CDN cache affect system performance?

Purging causes more requests to go to the origin server temporarily, which can increase load and latency until the cache is rebuilt.

What happens immediately after purging a CDN cache for a file?

A The CDN fetches the file fresh from the origin on next request

B The CDN serves the old cached file until expiration

C The file is deleted from the origin server

D The CDN disables caching for that file permanently

Purging removes the cached file so the CDN must get a fresh copy from the origin on the next request.

Which Azure service is used to manage CDN cache purging?

A Azure Virtual Machines

B Azure Blob Storage

C Azure CDN

D Azure Functions

Azure CDN service provides the tools to purge cached content on CDN endpoints.

Which purging method removes all cached content in Azure CDN?

A Purge by content path

B Invalidate by tag

C Refresh cache

D Purge everything

'Purge everything' clears all cached content on the CDN endpoint.

What is a potential downside of frequent CDN cache purging?

A Permanent loss of content

B Increased load on origin servers

C Slower CDN network speed

D Users see outdated content

Frequent purging causes more requests to origin servers, increasing their load temporarily.

Which HTTP header can help control CDN caching behavior?

A Cache-Control

B Content-Type

C Authorization

D User-Agent

The Cache-Control header instructs CDNs and browsers how to cache content.

Explain the process and reasons for purging CDN cache in Azure.

Think about how cached content can become outdated and how Azure lets you remove it.

Describe the difference between purging specific content paths and purging everything in CDN cache.

Consider when you want to update one file versus all files.