mx4kmodem90.marietta.ee.net has no CNAME records.
Question and response
Question
dig mx4kmodem90.marietta.ee.net. NS
Answer
The response has no answer records.
Authority
ee.net. 5905 SOA dns4.ee.net. hostmaster.ee.net. 2017030823 210800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0