otrs.dynu.com has no CNAME records.
Question and response
Question
dig otrs.dynu.com. NS
Answer
The response has no answer records.
Authority
dynu.com. 1004 SOA ns1.dynu.com. administrator.dynu.com. 76250800 1800 300 86400 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0