Peter Wilson

Taking the “distributed” out of CDN

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Peter Wilson

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Note: After publishing this article, I was given the results of traceroutes from other Australian cities. The results showed I was wrong.

Over on Twitter @bobearth, prompted me to run some trace routes against the Google CDN and compare it to the Microsoft CDN. It appears Google have taken the distributed network out of their CDN.

As you’re probably aware, CDN is an abbreviation for content distributed network. The idea behind them is that American users will be served content from a server located in the US or Canada, Australian users will be served content from a server located in Australia or the Pacific, and so on.

Doing a trace to the Google CDN from the Soupgiant HQ in Melbourne, I was expecting to receive a response a server in Sydney. Instead, the response came from California, USA as the final steps of this traceroute show:

127.0.0.1:~ peterwilson$ traceroute ajax.googleapis.com
[snip]
 5  syd-nxg-men-crt1-ge-3-1-0 (202.7.173.241)  27.479 ms  87.472 ms  78.234 ms
 6  202.7.171.46 (202.7.171.46)  91.118 ms  31.786 ms  27.314 ms
 7  66.249.95.232 (66.249.95.232)  80.358 ms
    66.249.95.234 (66.249.95.234)  27.842 ms
    66.249.95.232 (66.249.95.232)  44.059 ms
 8  209.85.249.52 (209.85.249.52)  177.570 ms
    66.249.95.166 (66.249.95.166)  172.656 ms  157.311 ms
 9  72.14.236.126 (72.14.236.126)  172.117 ms  153.304 ms  180.227 ms
10  googleapis.l.google.com (66.249.89.95)  178.725 ms  193.939 ms  181.227 ms

The response from Microsoft’s CDN were more to my liking:

127-0-0-1:~ peterwilson$ traceroute ajax.aspnetcdn.com
traceroute: Warning: ajax.aspnetcdn.com has multiple addresses; using 70.37.159.166
traceroute to ajax.aspnetcdn.com (70.37.159.166), 64 hops max, 52 byte packets
[snip]
 7  10gigabitethernet5-1.syd-xmx-edgcom-1b.ntwk.msn.net (70.37.149.62)  90.691 ms  86.004 ms  37.900 ms
 8  ajax.microsoft.com (70.37.159.166)  71.541 ms  83.053 ms  80.586 ms

This prompts the question: should I switch to serving jQuery and other hosted libraries to the Microsoft CDN? Both Google and Microsoft use a cookie-free domain for their CDNs, both are set to browser cache for 12 months. More sites use Google’s CDN to serve, but only Microsoft serve geographically near the majority of visitors to Soupgiant and Big Red Tin.

I don’t know the answer to this question. I do know that if Google’s CDN was distributed, there would be no question.

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