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IT & Tech Intermediate

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.

8 lessons 8 labs 2.2 h Certificate

  • One-time payment
  • 14-day money-back guarantee
  • Secure checkout with Stripe

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

  • Compute the request and byte hit ratios of Glimmerline's six content types, the correctly weighted totals for the month and find the content type the CDN serves worst.
  • Turn Glimmerline's edge traffic and hit ratios into origin requests per hour and per second, size the origin fleet per time slot and compare it with the fleet you would need without a CDN.
  • Split Glimmerline's 428.3 TB of monthly edge traffic across a five-tier price list, add the request fees and work out the effective price per TB.
  • Compare Glimmerline's monthly delivery cost with and without the CDN: internet egress, origin-to-CDN transfer, the CDN bill and the origin servers, and work out the saving in dollars and percent.
  • Model how popular Glimmerline's 100,000 article images are with a Zipf distribution, estimate the hit ratio at one edge for a given TTL and compare four TTL and cache-key scenarios.
  • Estimate the time to first byte (TTFB) for Glimmerline's visitors in six regions with and without the CDN, weighting hits and misses, and work out the user-weighted reduction.
  • Estimate how many TB per month Glimmerline saves by serving images at their displayed width and in a modern format, and value the saving at the right price per TB.
  • Forecast Glimmerline's CDN traffic for 12 months, price every month on pay-as-you-go and on a committed-volume contract, total the difference and chart both cost lines.

About this course

Every cache miss costs origin capacity, bandwidth and user patience. This course quantifies all three. You compare request and byte hit ratios by content type, then calculate the origin load and servers needed after offload. Billing labs apply tiered egress pricing to a monthly bill and compare total cost with and without a CDN. You model how TTL and cache-key choices change the hit ratio under a Zipf popularity curve, and weight edge and origin round trips to estimate latency gains. Image labs measure bytes saved by resizing and modern formats, and a traffic forecast informs a commit-contract decision. For web engineers, platform teams, SREs and technical product managers.

Curriculum

Course content

8 lessons · 8 labs · 2.2 h · final exam

  1. Request Hit Ratio vs Byte Hit Ratio by Content TypeLab15 min4 checked tasks
    Unlocked when you buy the course
  2. Origin Offload: Origin Load in Requests per Second & Servers NeededLab15 min4 checked tasks
    Unlocked when you buy the course
  3. Tiered Egress Pricing: the Monthly Bandwidth BillLab15 min4 checked tasks
    Unlocked when you buy the course
  4. Total Cost With vs Without a CDNLab15 min4 checked tasks
    Unlocked when you buy the course
  5. TTL & Cache-Key Choices: Hit Ratio from Zipf PopularityLab20 min4 checked tasks
    Unlocked when you buy the course
  6. Latency Gain: Edge vs Origin Round Trips Weighted by Hit RatioLab15 min4 checked tasks
    Unlocked when you buy the course
  7. Image Optimisation: Bytes Saved by Resizing & FormatLab15 min4 checked tasks
    Unlocked when you buy the course
  8. Traffic Forecast & the Commit-Contract Decision (Chart)Lab20 min4 checked tasks
    Unlocked when you buy the course
  9. Final exam12 questions, 75% to pass, unlimited retries.

Certificate

Finish with a certificate you can verify

Complete every lesson and pass the final exam to receive a certificate of completion for this course, with a unique credential ID and a public verification page.

  • Names the course, your score and the date of issue
  • A verification link for your CV or LinkedIn profile
  • 12 questions, 75% to pass, unlimited retries.

A Tutorvo certificate confirms that you completed a course. It is not an official or professional qualification.

Illustration. Your certificate shows your own name, course and credential ID.

Before you buy

Questions about this course

Is this a subscription?

No. You pay $9.99 once for this course. There is no subscription and nothing renews automatically. Prices are in US dollars; taxes may be added where required.

What exactly do I get?

All lessons and labs of this course, the final exam and the certificate, including later updates to the course, for as long as Tutorvo offers it. Access is personal and tied to your account.

Can I get a refund?

Yes. If you are not satisfied, email hello@tutorvo.com within 14 days of buying and we refund the course in full via Stripe. The guarantee does not apply once a certificate for the course has been issued to you, or where there are signs of abuse.

When can I start?

Right after payment. Access starts immediately at your request; for consumers in the EU/EEA the statutory right of withdrawal therefore ends once access has begun, while our 14-day money-back guarantee applies regardless.

Do I need Excel or other software?

No. The labs run in a spreadsheet inside your browser on a laptop, tablet or phone. Function names and syntax follow Excel.

Is the certificate an official qualification?

No. It confirms that you completed all lessons of the course and passed its final exam. It is not an official, state-recognised or professional qualification. The name is taken from your profile when the certificate is issued.

Full details are in our Terms · hello@tutorvo.com

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