Apex domains cannot have CNAME records.
Question and response
Question
dig host-telecom.com. NS
Answer
host-telecom.com. 5 NS alpha.host-telecom.com.
host-telecom.com. 5 NS gamma.host-telecom.com.
host-telecom.com. 5 NS beta.host-telecom.com.
Authority
The response has no authority records.
Additional
beta.host-telecom.com. 5 A 193.161.84.90
alpha.host-telecom.com. 5 A 91.109.200.200
gamma.host-telecom.com. 5 A 188.226.189.38
beta.host-telecom.com. 5 AAAA 2a03:1840:0:0:0:0:0:53
alpha.host-telecom.com. 5 AAAA 2a03:ec0:0:0:0:0:0:53
gamma.host-telecom.com. 5 AAAA 2a03:b0c0:0:1010:0:0:75:c001
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0