mail3.memset.com has no CNAME records.
Question and response
Question
dig mail3.memset.com. NS
Answer
The response has no answer records.
Authority
memset.com. 2134 SOA ns1.memset.com. hostmaster.memset.com. 1771778715 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0