IPv6 and CDN's

[Marco Davids via NANOG <nanog () nanog org>]

Hi!

We currently live in times where is actually fun to go IPv6-only. In my 
case, as in: running a FreeBSD kernel compiled without the IPv4-stack.

A few years back doing such thing was mostly disappointing, but nowadays 
is actually quite doable and entertaining.

So, the other day I decided to take this experiment to the next level by 
disconnecting my local resolver from IPv4 as well.

Then things started to break. LinkedIn, Bing, Openstreetmap... Although 
they all work great on IPv6-only, now they no longer did.

It turns out that there underlying CDN's with domain names such as 
‘l-msedge.net’ and ‘trafficmanager.net’ (Microsoft) or 'fastly.net', 
that reside on authoritative name servers that *only* have an IPv4 address.

I guess my question is simple: Why?

Are there good architectural reason for this? Or is it just something 
that is overlooked and forgotten about?

I would love to find out!

Thank you.

--
Marco

This is also fun by the way. Look at that nice banner on 
https://clintonwhitehouse2.archives.gov/ :-)