mte2._domainkey.mark-on.dk has no NS records.
NS records for this zone are defined at mark-on.dk.
NS records for this zone are defined at mark-on.dk.
Question and response
Question
dig dkim2.mandrillapp.com. NS
Answer
The response has no answer records.
Authority
mandrillapp.com. 900 SOA ns-720.awsdns-26.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0