pop.successinet.com has no CNAME records.
Question and response
Question
dig pop.successinet.com. NS
Answer
The response has no answer records.
Authority
successinet.com. 3184 SOA ns1.successinet.com. hostmaster.successinet.com. 2018042516 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0