What is the standard propagation time for a CDN?

Question

I'm a bit confused about the propagatation time for a CDN. We already have a CDN that contain all of our static files. I'm trying to see if CDN is a good choice for a new project.

Basically, how many time it will take to see my updated file in the CDN ?

Is there any way to reduce time to replicate ?

FYI, i'm using LimeLight but my question is for all CDN.

Answer 1

Propagation depends on filesize and cache settings.

For small files (varies by CDN but typically includes all files under 10MB individual filesize) such as images, css, js, etc. the propagation is instant.

If a file is not in cache, the CDN will fetch it at the first request and then continue caching it until it expires. The standard is a 24 hour cache expiry, but most CDNs allow you to configure it and let it be cached for longer.

For large files (any files over 10MB individual filesize) such as videos, propagation typically varies between 2 - 12 hours, depending on the CDN and how much priority they give you as a client.

You can easily test if a file has propagated fully by doing a curl against the IP of each edge location/server.