Apex domains cannot have CNAME records.
Question and response
Question
dig arsystel.com. NS
Answer
arsystel.com. 5 NS ns-arsys.ui-dns.biz.
arsystel.com. 5 NS ns-arsys.ui-dns.es.
arsystel.com. 5 NS ns-arsys.ui-dns.org.
arsystel.com. 5 NS ns-arsys.ui-dns.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0