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There has always been an extra DNS lookup wirh a CDN. Thats even the point of the CDN since based on where you are, you will be served from a location as physic

There has always been an extra DNS lookup wirh a CDN. Thats even the point of the CDN since based on where you are, you will be served from a location as physically close to you as possible. Where did you get the information from that CDNs arent as good as they used to be?

richeyryan 6y ago
Safari and Chrome now use a combined cache strategy using the URL of the resource and the top level domain of the site loading that resource as the cache key. For scenarios that were previously popular like using the jQuery CDN, you won't get the benefit of the user having jQuery in their cache from another website. You will however still get the proximity benefit you describe. CDNs are obviously still quite useful, just not for getting cache hits on popular libraries. https://www.stefanjudis.com/notes/say-goodbye-to-resource-caching-across-sites-and-domains/ https://www.stefanjudis.com/notes/say-goodbye-to-resource-ca...
- chris_engel 6y ago
  Yeah thats true - so you explicitly mean CDNs that serve a single thing only. Using a CDN for your static files is just as fine as it always has been.
eyelidlessness 6y ago
> Where did you get the information from that CDNs arent as good as they used to be? The other comment addressed this, but to be clear. One of the common usage of external CDN resources is predicated on a performance benefit: if multiple sites use the same resource, it’s more likely to be cached already and much less likely to be impaired by the drawbacks (DNS hit, external network factors). But since browsers have shipped cache partitioning for very good privacy reasons (as other comment mentions, caches are prefixed by the requesting origin), you get no cache benefit and all of the detriment of a clear cache. Essentially the only reason to use a CDN for third party resources now is if you can bet the CDN will perform better than your local, already DNS-resolved host.

richeyryan 6y ago

Safari and Chrome now use a combined cache strategy using the URL of the resource and the top level domain of the site loading that resource as the cache key. For scenarios that were previously popular like using the jQuery CDN, you won't get the benefit of the user having jQuery in their cache from another website. You will however still get the proximity benefit you describe. CDNs are obviously still quite useful, just not for getting cache hits on popular libraries. https://www.stefanjudis.com/notes/say-goodbye-to-resource-caching-across-sites-and-domains/ https://www.stefanjudis.com/notes/say-goodbye-to-resource-ca...

chris_engel 6y ago
Yeah thats true - so you explicitly mean CDNs that serve a single thing only. Using a CDN for your static files is just as fine as it always has been.

eyelidlessness 6y ago

> Where did you get the information from that CDNs arent as good as they used to be? The other comment addressed this, but to be clear. One of the common usage of external CDN resources is predicated on a performance benefit: if multiple sites use the same resource, it’s more likely to be cached already and much less likely to be impaired by the drawbacks (DNS hit, external network factors). But since browsers have shipped cache partitioning for very good privacy reasons (as other comment mentions, caches are prefixed by the requesting origin), you get no cache benefit and all of the detriment of a clear cache. Essentially the only reason to use a CDN for third party resources now is if you can bet the CDN will perform better than your local, already DNS-resolved host.