Apex domains cannot have CNAME records.
Question and response
Question
dig mailpro.myfasthosting.com. NS
Answer
mailpro.myfasthosting.com. 1 NS ns1.hoasted.nl.
mailpro.myfasthosting.com. 1 NS ns2.hoasted.eu.
mailpro.myfasthosting.com. 1 NS ns3.hoasted.com.
Authority
The response has no authority records.
Additional
ns1.hoasted.nl. 1 A 164.92.214.194
ns2.hoasted.eu. 1 A 172.233.48.234
ns1.hoasted.nl. 1 AAAA 2a03:b0c0:2:d0:0:0:14d9:d001
ns2.hoasted.eu. 1 AAAA 2600:3c0e:0:0:f03c:93ff:fe55:40b0
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0