ptr6.routit.net has no NS records.
NS records for this zone are defined at routit.net.
NS records for this zone are defined at routit.net.
Question and response
Question
dig ptr6.routit.net. NS
Answer
The response has no answer records.
Authority
routit.net. 900 SOA auth01-peer.ib.routit.net. noc.routit.nl. 287 1800 900 604800 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0