HighPerformanceWebSites

1 200 ok date fri 30 oct 1998 131941 gmt server

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Unformatted text preview: •  amazon.com aol.com cnn.com ebay.com google.com msn.com myspace.com wikipedia.org yahoo.com youtube.com Akamai Akamai •  Akamai, Mirror Image •  SAVVIS Akamai, Limelight Akamai Content DistribuOon Networks have servers around the world They distribute your content so downloads can come from a nearby locaOon Major CDN providers are –  Akamai •  –  –  –  –  –  Distributes OS X and iOS updates SAVVis Limelight OnApp BityGravity Amazon CloudFront distribute your static content before distributing your dynamic content Copyright 2009 - 2013 Horowitz 14 Rule 3: Add an Expires Header •  All caches use a set of rules to determine whether to deliver an object from the cache or request a new version –  –  –  If the object’s headers tell the cache not to keep the object, it won’t If the object is authenOcated or secure, it wont be cached A cached object is “fresh” (able to be sent to a client without checking with the server) if •  It has an expiry Ome or other age- controlling direcOve that is set and sOll within the fresh period •  If a browser cache has already seen the object and has been set to check once a session •  If a proxy cache has seen the object recently, and it was modified long ago –  If an object is “stale”, the origin server will be asked to validate the object or tell the cache whether the copy that is has is sOll good •  As part of HTTP protocol there is a Cache- Control header •  HTTP headers are sent by the server before the HTML, and only seen by the browser and any intermediate caches....
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