I have a curious problem being served sub-optimal CDN servers when using opendns or googledns
I am in London/UK and opendns appears not to have a local DNS cache, so attempting to access bbc.co.uk and view the page images gives these results: # dig news.bbcimg.co.uk ; <<>> DiG 9.7.3 <<>> news.bbcimg.co.uk ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57231 ;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;news.bbcimg.co.uk. IN A ;; ANSWER SECTION: news.bbcimg.co.uk. 2413 IN CNAME newsimg.bbc.net.uk. newsimg.bbc.net.uk. 202 IN CNAME news.bbc.co.uk.edgesuite.net. news.bbc.co.uk.edgesuite.net. 3427 IN CNAME a1733.g.akamai.net. a1733.g.akamai.net. 10 IN A 216.246.75.138 a1733.g.akamai.net. 10 IN A 216.246.75.113 ;; Query time: 84 msec ;; SERVER: 192.168.105.212#53(192.168.105.212) ;; WHEN: Fri Jul 8 10:22:02 2011 ;; MSG SIZE rcvd: 168 That ip range is in the USA and about 85ms away from me. Instead using google dns I get: # dig news.bbcimg.co.uk @8.8.4.4 .. a1733.g.akamai.net. 19 IN A 193.28.236.135 a1733.g.akamai.net. 19 IN A 193.28.236.136 These are 41ms away If I switch to my ISP DNS servers: # dig news.bbcimg.co.uk @212.69.36.3 .. a1733.g.akamai.net. 15 IN A 92.123.154.18 a1733.g.akamai.net. 15 IN A 92.123.154.33 These are 15ms away So having discovered that using nominally faster DNS servers has amongst other things the disadvantage that CDNs might pass you to suboptimal choices, hurting you multiple times per web page... So I tried this configuration: server=8.8.4.4 server=/akamai.net/212.69.36.3 server=/edgesuite.net/212.69.36.3 But I notice that since the reply comes back in a single response that the CNAMES are not resolved using the alternative server parts. Disregarding all the privacy debates about using these super DNS servers, does anyone have any thoughts on how to better handle getting redirected to a local CDN, other than perhaps using only the ISP servers? Thanks Ed W
