CDN Monitoring & Troubleshooting 3

Question 1

What is the purpose of real user monitoring (RUM) in a CDN context?

Accepted Answer

Collecting performance data from actual end-user browsers to measure true delivery quality

Answer

RUM collects telemetry from real browsers (TTFB, FCP, page load time) to measure actual CDN delivery performance as experienced by users.

Question 2

A CDN is configured with a 1-hour TTL for static assets, but marketing needs instant cache invalidation capability. Which approach adds that capability without changing TTL?

Accepted Answer

Implement cache versioning via URL fingerprinting (e.g., file.abc123.css)

Answer

URL fingerprinting embeds a content hash in the filename, making updated files unique URLs that bypass existing cache entries without needing purge operations.

Question 3

Which CDN metric directly measures the percentage of bytes served from cache versus fetched from origin?

Accepted Answer

Offload ratio (byte offload rate)

Answer

Byte offload ratio measures what fraction of total data volume was served from CDN cache, reflecting cost savings and origin protection effectiveness.

Question 4

An HTTP/2 multiplexed connection through a CDN suddenly degrades to HTTP/1.1 behavior. Which log entry would confirm this regression?

Accepted Answer

Protocol field showing 'http/1.1' instead of 'h2' in access logs

Answer

The protocol field in CDN access logs records whether h2 or http/1.1 was negotiated; a shift to http/1.1 confirms the HTTP/2 multiplexing regression.

Question 5

A CDN operator receives alerts that origin health checks are failing for one of two origin servers in a load-balanced pool. What is the immediate CDN-level response?

Accepted Answer

The CDN automatically removes the unhealthy origin from rotation and routes all traffic to the healthy one

Answer

CDN origin health check systems automatically failover by removing unhealthy origins from the load-balancing pool to prevent routing traffic to unavailable servers.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN Monitoring & Troubleshooting 3