Quote from the AS112 Project Home Page:

Because most answers generated by the Internet's root name server system are negative, and many of those negative answers are in response to PTR queries for RFC1918 and other ambiguous addresses, as follows:

• 10.0.0.0/8
• 172.16.0.0/12
• 169.254.0.0/16
• 192.168.0.0/16

There are now separate (non-root) servers for these queries...

TREX hosts an instance of the AS112 anycast servers. Members can get access to them by peering with TREX's BGP routers and accepting the following routes from them:

route:          192.175.48.0/24
descr:          Root Server Technical Operations Assn
descr:          See: http://www.as112.net/
descr:          $Id: route:192.175.48.0-24,v 1.3 2010-05-20 10:35:04 nico Exp $
origin:         AS112
mnt-by:         NETNOD-MNT
source:         RIPE # Filtered

route6:         2620:4f:8000::0/48
descr:          AS112 Project IPv6 network
origin:         AS112
admin-c:        OARCA-ARIN
tech-c:         OARCA-ARIN
remarks:        Driect Assignment for AS112 project, http://public.as112.net/
mnt-by:         MAINT-AS2884
source:         OTTIX # Filtered