ns2.duohemoglobin.com has no CNAME records.
Question and response
Question
dig ns2.duohemoglobin.com. NS
Answer
The response has no answer records.
Authority
duohemoglobin.com. 2844 SOA ns.duohemoglobin.com. kiki\.kwad.gmail.com. 1769616822 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0