Why is the default registration URL now subscription.rhsm.redhat.com?

Issue

Previously /etc/rhsm/rhsm.conf had the hostname set to:

hostname = subscription.rhn.redhat.com

In more recent versions of subscription-manager, there is a new default:

hostname = subscription.rhsm.redhat.com

This will be the new endpoint for communication needed for Registering and Subscribing to Red Hat Subscription Management.
For the time being, both will operate the same but are actually different endpoints which point to different servers / IP Addresses.
- Take care of which are made use of in your environment, as you may need to open both endpoints in your environment based on what you have deployed.