What belongs on a CDN

A results portal is fine all year and collapses for two hours every results day. The traffic on that day is roughly 200 times normal.

A page load consists of:

• the HTML page, different for each student
• a 2 MB logo and stylesheet bundle, identical for everyone
• a 40 KB result PDF, different for each student

All three are served by one origin server in the college data centre.

Measured on results day: 94% of bytes leaving the origin are the logo and stylesheet bundle, requested afresh by every student on every page load.