CDN & Caching Economics: Hit Ratio, Origin Offload & Egress Cost
Request vs byte hit ratio, origin load and servers, tiered egress bills, cost with vs without a CDN, TTL and cache-key choices on Zipf popularity, latency gain, image savings and a commit-contract decision: 8 labs on one fictional media site.
The first lesson is free — no account needed.
About this course
A CDN and caching economics course that runs the delivery numbers of one fictional online magazine, Glimmerline, in a spreadsheet, for web and platform engineers, SREs, FinOps and media operations staff, and technical product managers. You compute request and byte hit ratios by content type with correctly weighted totals, turn edge traffic into origin requests per second and servers needed, price 428.3 TB a month across a tiered egress price list, compare the total delivery cost with and without a CDN, estimate hit ratios for TTL and cache-key choices from Zipf popularity, weight time to first byte by hit ratio across six regions, value the bytes saved by resizing images and modern formats, and forecast traffic to choose between pay-as-you-go and a commit contract in a chart. Illustrative prices, with no affiliation with any CDN or cloud vendor. The first lab is free.
Lessons
- Request Hit Ratio vs Byte Hit Ratio by Content TypeFree
- Origin Offload: Origin Load in Requests per Second & Servers Needed Pro
- Tiered Egress Pricing: the Monthly Bandwidth Bill Pro
- Total Cost With vs Without a CDN Pro
- TTL & Cache-Key Choices: Hit Ratio from Zipf Popularity Pro
- Latency Gain: Edge vs Origin Round Trips Weighted by Hit Ratio Pro
- Image Optimisation: Bytes Saved by Resizing & Format Pro
- Traffic Forecast & the Commit-Contract Decision (Chart) Pro