CDN node locations

Phil Bedard bedard.phil at
Sun Nov 17 02:08:06 UTC 2013

Maybe "proxy" was the wrong word, and "transparent video optimization" are
better words.  :)  I'm not speaking with any internal knowledge of Sprint
Wireless's network but I wouldn't be surprised if you had no choice in the


From:  Jay Ashworth <jra at>
Date:  Saturday, November 16, 2013 at 8:56 PM
To:  Phil Bedard <bedard.phil at>, NANOG <nanog at>
Subject:  Re: CDN node locations

Maybe, but I don't use their proxies, I've overriden them for speed.

Phil Bedard <bedard.phil at> wrote:
> On 11/16/13, 7:36 PM, "Jay Ashworth" <jra at> wrote:
>>> Second, a list of CDN nodes is likely impossible to gather & maintain
>>> without the help of the CDNs themselves. There are literally thousands
>>> of them, most do not serve the entire Internet, and they change
>>> frequently. And before you ask, I know at least Akamai will _not_ give
>>> you their list, so don't even try to ask them.
>> I find myself unsurprised.
>> I was led to a very interesting failure case involving CDN's a couple
>> weeks
>> ago, that I thought you might find amusing.
>> I have a Samsung Galaxy S4, with Sprint.  On a semi-regular basis, the
>> networking gets flaky around
>>  1-2am
>> ish local time, but 3 weekends ago,
>> the symptom I saw was DNS lookups failed -- and it wasn't clear to me
>> whether it was "just some lookups failed", or that Big Sites were cached
>> at the provider, and *all* outgoing 53 traffic to the greater internet
>> wasn't being forwarded by Sprint's customer resolvers.
>> I know that it was their resolvers, though, as I grabbed a copy of Set
>> DNS, 
>> and pointed my phone to <> , and
>> <> , and OpenDNS, and like that,
>> and everything worked ok.
>> Except media.
>> (Patrick is starting to nod and chuckle, now :-)
>> Both YouTube and The Daily Show's apps worked ok, but refused to play
>> video clips for me.  If I reset the DNS to normal, I went back to "not
>> all sites are reachable, but media plays fine".
>> My diagnosis was that those sites were CDNed, and the DNS names to *which*
>> they were CDNs wer
>>  e only
>> visible inside Sprint's event horizon, so when I
>> was on alternate DNS resolution, I couldn't get to them.
>> But that took me over a day to figure out.  Don't get old.  :-)
>> Patrick?  Is that how (at least some) customers do it?
> It seems more likely the Sprint resolvers you were using were having
> difficulty reaching external authoratative servers but the devices they
> proxy all the media content through wasn't...  All major media content
> these days is CDN'd but I don't think that had anything to do with it.
> Phil 

Sent from my Android phone with K-9 Mail. Please excuse my brevity.

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