Per-Entity Metadata Working Group

[Patrick Radtke <>]

On Wed, Sep 14, 2016 at 12:16 PM, Nick Roy 
<>
 wrote:
> That is exactly why having at least one CDN, and preferably more than one,
> is relevant to a failover strategy.  Geographic and logical redundancy.
> Publishing to more than one CDN than one means you can configure clients to
> fail over between more than one service.  Keeping the naming separate and
> putting the failover between CDNs in the client lets clients specify
> parameters they are comfortable with for things like latency.


I was curious about the tradeoff between having clients configure CDN
failover vs using round robin DNS that returned CNAMEs to each CDN.
For the latter, in the event of a single CDN outage, a less
intelligent client would at least hit a good CDN half the time and
cache the result - but this assumes a unintelligent client will cycle
through the DNS records returned. According to this
http://stackoverflow.com/a/7204522/54396 Java does not do so by
default. I'm not that familiar with .Net, but it seems to default to
'No' as well: 
https://msdn.microsoft.com/en-us/library/system.net.servicepointmanager.enablednsroundrobin(v=vs.110).aspx

Anyhow, my conclusion from reading is that most clients will likely
just hit the first IP in the DNS cache and not cycle through the
others.

-Patrick