CDN CDN Origin Shield & Pull/Push Zones 2

Question 1

An operator uses a CDN push zone to distribute a software installer. After uploading a new version, users still receive the old file. What is the most likely cause?

Accepted Answer

Edge nodes are serving cached copies of the old file; a purge or cache invalidation is required

Answer

Push zone edge nodes cache uploaded files; replacing a file at the origin/storage does not automatically evict cached copies, so a targeted purge is required.

Question 2

Which CDN feature allows operators to set different cache TTLs at the origin shield layer versus the edge PoP layer?

Accepted Answer

Surrogate-Control header or CDN-specific cache directives

Answer

Headers like Surrogate-Control (Fastly) or CDN-Cache-Control allow operators to specify longer TTLs at the shield/CDN layer independently of the browser-facing Cache-Control.

Question 3

What is the trade-off of placing origin shield in a region geographically distant from the origin server?

Accepted Answer

Higher cache-hit ratio but increased latency for cache misses that must travel further to origin

Answer

A distant shield improves global cache consolidation but adds round-trip latency on cache misses since the shield must fetch from a far origin, increasing time-to-first-byte for uncached requests.

Question 4

A CDN pull zone is configured with a 1-hour TTL. The origin content is updated. What must the operator do to immediately serve fresh content?

Accepted Answer

Issue a cache purge/invalidation for the affected URLs

Answer

A cache purge removes the stale object from CDN nodes before TTL expiry, ensuring the next request fetches and caches the updated content from origin.

Question 5

What HTTP mechanism allows an origin server to validate a cached object at the shield without transferring the full response body?

Accepted Answer

Conditional requests using ETag or Last-Modified headers (304 Not Modified)

Answer

Conditional GET requests let the shield send an If-None-Match or If-Modified-Since header; the origin returns 304 Not Modified if unchanged, saving bandwidth on revalidation.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN CDN Origin Shield & Pull/Push Zones 2