api.dynu.com has no CNAME records.
Question and response
Question
dig api.dynu.com. NS
Answer
The response has no answer records.
Authority
dynu.com. 2776 SOA ns1.dynu.com. administrator.dynu.com. 76187930 1800 300 86400 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0