CDN Monitoring & Troubleshooting 2

Question 1

Which metric best indicates that a CDN edge node is experiencing cache thrashing?

Accepted Answer

Rapid alternation between cache HIT and MISS for the same object

Answer

Cache thrashing occurs when objects are repeatedly evicted and re-fetched, causing rapid HIT/MISS alternation for identical cache keys.

Question 2

A CDN operator notices that certain users in the Pacific Northwest are receiving stale content even after purging. What should be investigated first?

Accepted Answer

Whether the purge propagated to all edge POPs in that region

Answer

Purge propagation delays to specific edge POPs can cause localized stale content delivery even after a global purge is issued.

Question 3

What does a sudden spike in 5xx errors from a CDN edge while the origin server shows normal health indicate?

Accepted Answer

A configuration error was recently deployed to the CDN edge layer

Answer

When origin is healthy but CDN returns 5xx errors, a recent edge configuration change (routing rules, caching directives, security policies) is the most likely cause.

Question 4

Which tool is most appropriate for diagnosing which CDN POP a specific end user is being routed to?

Accepted Answer

nslookup with the local resolver to identify the returned IP

Answer

Running nslookup or dig from the user's local resolver reveals the edge IP assigned by the CDN's Anycast or GeoDNS, identifying the serving POP.

Question 5

A CDN dashboard shows high origin shield miss rates. What is the most likely impact?

Accepted Answer

Increased load and cost on the origin server

Answer

High origin shield misses mean requests are frequently bypassing the shield and hitting the origin, increasing origin load and egress costs.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN Monitoring & Troubleshooting 2