Apex domains cannot have CNAME records.
Question and response
Question
dig telehouse.bg. NS
Answer
telehouse.bg. 5 NS ns2.telehouse.bg.
telehouse.bg. 5 NS ns.telehouse.bg.
Authority
The response has no authority records.
Additional
ns.telehouse.bg. 5 A 178.132.80.6
ns2.telehouse.bg. 5 A 178.132.83.6
ns.telehouse.bg. 5 AAAA 2a01:8740:8740:91c:178:132:80:6
ns2.telehouse.bg. 5 AAAA 2a01:8740:8740:91c:178:132:83:6
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0