Cost Optimization & Traffic Management Flashcards

A CDN customer commits to 100 TB/month of data transfer under a reserved-capacity contract but only uses 60 TB. What is the likely financial outcome?

Answer: They pay for the full 100 TB committed regardless of usage

Reserved-capacity contracts typically require payment for the committed amount whether or not the full volume is consumed.

What is 'CDN request collapsing' and how does it reduce costs?

Answer: Queuing duplicate simultaneous cache-miss requests so only one goes to origin

Request collapsing (also called request coalescing) holds duplicate in-flight cache-miss requests and serves them all with a single origin response, reducing origin load.

A CDN administrator wants to minimize log storage costs. Which approach is most cost-effective without losing critical visibility?

Answer: Use log sampling and aggregate metrics with alerting on anomalies

Log sampling reduces storage volume while aggregate metrics and anomaly alerts preserve operational visibility at a fraction of the full-log storage cost.

Which CDN cost lever has the most direct impact on reducing 'cache fill' costs from origin to edge nodes?

Answer: Using origin shield (mid-tier caching) to consolidate origin requests

An origin shield acts as a central cache tier that absorbs redundant requests from multiple PoPs, dramatically reducing the number of fills that reach the origin.

A video platform uses adaptive bitrate (ABR) streaming. How does CDN configuration of ABR manifest files affect cost optimization?

Answer: Caching ABR manifests with short TTLs reduces origin polling while keeping streams current

Short-TTL caching of ABR manifests balances manifest freshness for live streams with reduced origin request volume, lowering both latency and costs.

What CDN concept describes the percentage of requests served from cache without hitting the origin?

Answer: Origin offload rate (cache hit ratio)

The cache hit ratio (origin offload rate) measures what fraction of total requests are served from edge cache; a higher ratio means lower origin costs.

A company's CDN costs spike every weekend due to user-generated video uploads triggering transcoding and delivery. Which strategy best controls these costs?

Answer: Use scheduled off-peak transcoding jobs and set upload size limits

Scheduling transcoding during off-peak hours and enforcing upload size limits reduces simultaneous compute and delivery costs during high-demand periods.