ipam.tue.nl has no CNAME records.
Question and response
Question
dig ipam.tue.nl. NS
Answer
The response has no answer records.
Authority
tue.nl. 705 SOA ipam.tue.nl. hostmaster.tue.nl. 34720 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0