ns2.de.colt.net has no CNAME records.
Question and response
Question
dig ns2.de.colt.net. NS
Answer
The response has no answer records.
Authority
de.colt.net. 3492 SOA ns0.de.colt.net. hostmaster.de.colt.net. 2010120210 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0