smtp.nanolearning.com has no CNAME records.
Question and response
Question
dig smtp.nanolearning.com. NS
Answer
The response has no answer records.
Authority
nanolearning.com. 3600 SOA ns1.hyp.net. hostmaster.domeneshop.no. 1771832997 14400 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0