Regarding Name Collision
ICANN (the governing organization for the internet) requires that non-existing domain names that occurred in the day-in-the life record of a zone before the TLD was added to the internet not resolve (be put on "server hold") until mitigation efforts are completed. The mitigation efforts are to ensure that no one is actually using the domain name on in internal network, because if they are, resolving that name also on the world-wide internet could cause some unwanted behavior.
In most cases the existence of the name in the zone before the TLD was added to the internet is due to browser searches for that name, so there is very little real risk.
The core of the issue is, names on the collision list must not resolve on the internet until ICANN feels any risk of unwanted behavior has been mitigated.
You can read all about this issue, known as Name Collision, or NXD, here
and here ;
UPDATE: ICANN has issued a final mitigation plan (See http://support.donuts.co/hc/en-us/articles/201858415-Have-you-seen-127-0-53-53-Helpful-Name-Collision-Mitigation-Guide), that requires all names on the Name Collision lists be put into a 90 day Controlled Interruption period. During this time, names on the list will resolve to 127.0.53.53, which should indicate to the network operator that their internal network has been misconfigured and needs fixing.
After the 90 days of Controlled Interruption, Donuts will release names that have bee reserved solely for name collision reasons, for sale. We expect this to happen in early January, 2015.