CDN Content Distribution & Caching 4

Question 1

When a CDN performs 'cache key normalization', what is the main benefit?

Accepted Answer

Increasing cache hit rates by stripping irrelevant query parameters from the cache key

Answer

Normalizing cache keys (e.g., removing tracking parameters like 'utm_source') prevents duplicate cache entries for functionally identical URLs.

Question 2

Which HTTP response code from origin tells a CDN to serve the cached version of a resource (if available) because origin is temporarily unavailable?

Accepted Answer

All of these may trigger stale-if-error serving

Answer

The 'stale-if-error' directive allows CDNs to serve stale cache on any 5xx or network error from origin.

Question 3

What is 'Surrogate-Control' header primarily used for in CDN caching?

Accepted Answer

Passing CDN-specific cache directives that CDNs honor but browsers ignore

Answer

Surrogate-Control lets origin set CDN TTLs independently from browser TTLs since CDNs consume and strip this header before forwarding.

Question 4

A news website uses URL-based cache invalidation but realizes it cannot purge all edge nodes fast enough during breaking news. What pattern best addresses this?

Accepted Answer

Use versioned URLs with short TTLs so updates deploy new URLs instantly

Answer

Versioned URLs (cache-busting) guarantee fresh content without relying on purge propagation speed, as new URLs start with empty caches.

Question 5

Which caching layer sits closest to the end user in a typical multi-tier CDN architecture?

Accepted Answer

Edge PoP (leaf node)

Answer

Edge PoPs (leaf nodes) are geographically distributed closest to users and handle the initial request before escalating to parent caches.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN Content Distribution & Caching 4