problem with www.xbox.com / akamai

[niels=cluenet at bakker.net]

* thomas at cis.uni-muenchen.de (Thomas Schäfer) [Sat 14 Jun 2014, 18:50 CEST]:
>thomas at diener:~> host www.xbox.com
[...]

>thomas at diener:~> ping6 www.xbox.com
>unknown host
>thomas at diener
>
>But sometimes it works.
>
>Is it an resolver-problem, or is the network not stable, or is it PEBKAC?

This is a problem with Microsoft's loadbalancing nameserver 
implementation, it seems.  They return CNAME when asked for A but no 
CNAME when asked for AAAA.

The chain is as follows:

www.xbox.com -> ns[1-6].msft.net say CNAME for www.gtm.xbox.com ->
ns*-*.gtm.xbox.com respond with empty in case of AAAA and CNAME
wildcard.xbox.com-c.edgekey.net when queried for A.

You see this working sometimes because if you asked first for A then 
your resolver will know the CNAME and while the TTL of 30 seconds 
hasn't yet expired it will know where to ask for AAAA records (Akamai).


>Can anybody confirm this problem, or suggest a better test?

Talk to Microsoft, their GLSB code is out of spec.  And it will break 
visiting xbox.com for all dual-stacked hosts, and for everybody else 
in the next 300 seconds, if the cache was empty!

I'm Cc'ing Mehmet who knows something (heh) about DNS and is with 
Microsoft.


	-- Niels.

-- 
"It's amazing what people will do to get their name on the internet, 
 which is odd, because all you really need is a Blogspot account."
			-- roy edroso, alicublog.blogspot.com