CDN Edge Computing & Edge Functions 5

Question 1

What is the role of the Cache-Tag (or surrogate key) header in edge computing deployments?

Accepted Answer

It associates cached responses with logical tags so they can be purged in bulk with a single API call

Answer

Cache-Tag / surrogate key headers let operators invalidate groups of related cached objects atomically without knowing exact URLs.

Question 2

Which of the following correctly describes the execution environment difference between Cloudflare Workers and AWS Lambda@Edge?

Accepted Answer

Workers run in V8 Isolates with sub-millisecond cold starts; Lambda@Edge runs in full Node.js containers with higher cold-start latency

Answer

Cloudflare Workers use lightweight V8 Isolates for near-zero cold starts, while Lambda@Edge runs in managed containers with higher initialization overhead.

Question 3

What does 'fan-out' mean in the context of edge function subrequests?

Accepted Answer

An edge function making multiple parallel upstream requests to assemble a composite response

Answer

Fan-out allows an edge function to fetch data from several microservices or APIs concurrently, then merge the results into one response for the client.

Question 4

A streaming edge function uses the TransformStream API. What is the main benefit over a buffered response approach?

Accepted Answer

It reduces Time To First Byte by piping response chunks to the client as they arrive rather than waiting for the full response

Answer

Streaming responses let the edge begin forwarding data to the client immediately, improving perceived performance for large or slow-generating payloads.

Question 5

What is 'stale-while-revalidate' (SWR) and what problem does it solve at the edge?

Accepted Answer

A caching directive that serves a stale cached response immediately while refreshing the cache in the background, eliminating latency spikes on cache expiry

Answer

SWR decouples cache freshness from user-facing latency so users always get a fast cached hit while the edge silently updates the entry for the next request.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN Edge Computing & Edge Functions 5