In a CDN’d world, OpenDNS is the enemy

The_PHP_Jedi writes: "Alternative DNS services, such as OpenDNS and Google Public DNS, are used to bypass the sluggishness often associated with local ISP DNS servers. However, as more Web sites, particularly smaller ones, use Content Distribution Networks (CDNs) via embedded ads, widgets and other assets, the effectiveness of non-ISP DNS servers may be undermined. Why? Because CDNs rely on the location of a user's DNS server to determine the closest server with the hosted content. Sajal Kayan published a series of test results which demonstrates the difference, and also provided the Python script used so you can test which is the most effective DNS service for your own Internet connection."

Stupid

[jgreco]

Stooooo-pid. DNS is only one small part of it all. You only /need/ to use DNS based location guessing for the initial page load to a website. Once there, the website's CGI code gets the user's actual IP address, and can generate a dynamic page containing proper references to CDN-based images based on actual location, etc. The initial page load is typically only a few dozen kilobytes, and it doesn't matter too much if it's coming from the opposite side of the planet, but because OpenDNS and other major p

Re:

[sajalkayan]

Yes the website's CGI code *can* generate different URLs for images/static content based on IP but almost nobody does that, cause its very expensive to generate and makes server side caching useless. Almost all CDN services use DNS to figure out and point users to the nearest POP. Even slashdot.org is serving static assets from the hostname a.fsdn.com which is served via akamai. i count 19 requests to http://a.fsdn.com/* [fsdn.com] on a single pageload of /. which is currently served by a server within my ISPs networ