Apex domains cannot have CNAME records.
Question and response
Question
dig retelit.net. NS
Answer
retelit.net. 5 NS down.spin.it.
retelit.net. 5 NS up.spin.it.
retelit.net. 5 NS strange.as6734.net.
Authority
The response has no authority records.
Additional
up.spin.it. 5 A 79.143.126.250
down.spin.it. 5 A 79.143.126.251
strange.as6734.net. 5 A 82.193.34.154
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0