If you were to give a cursory glance at the top list on WebHosting.info you would have to be forgiven for not thinking that there are some very odd patterns:
A disproportionate number of the nameservers listed would appear to belong to domain parking companies, while the remainder would probably have a large percentage of “parked” domains as well.
While there is nothing wrong with parking domains and monetising them it is worrying to think that such a large portion of the internet is not actually “alive” at any given time.