CDN Content Distribution & Caching 5

Question 1

A CDN edge node receives a 'Vary: Accept-Encoding' header from origin. What does this instruct the CDN to do?

Accepted Answer

Cache separate versions of the resource based on the Accept-Encoding request header value

Answer

The Vary header tells the CDN to store distinct cached copies for each unique value of the specified request header (e.g., gzip vs. br vs. identity).

Question 2

What is 'cache stampede' (also called 'thundering herd') in CDN caching, and what is the primary mitigation?

Accepted Answer

When too many CDN nodes overload origin simultaneously; mitigated by request coalescing

Answer

Cache stampede occurs when a popular cached item expires and hundreds of simultaneous requests all miss and hit origin; request coalescing lets only one through.

Question 3

Which HTTP/2 feature can CDNs leverage to push content to browsers before they request it, reducing round trips?

Accepted Answer

HTTP/2 Server Push

Answer

HTTP/2 Server Push allows CDN edge nodes to proactively send resources (CSS, JS) to the client alongside the initial HTML response.

Question 4

A CDN is configured with 'stale-while-revalidate=60'. What happens during that 60-second window?

Accepted Answer

The CDN serves the stale cached response immediately while asynchronously fetching a fresh copy in the background

Answer

stale-while-revalidate lets the CDN return stale content instantly (zero latency penalty) while triggering a background refresh within the window.

Question 5

Which content type is generally LEAST suitable for aggressive CDN caching with long TTLs?

Accepted Answer

Product listing pages with real-time inventory and pricing

Answer

Product pages with live inventory and pricing change frequently and vary per user, making long TTLs inappropriate without smart invalidation.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN Content Distribution & Caching 5