Apex domains cannot have CNAME records.
Question and response
Question
dig dns.sa. NS
Answer
dns.sa. 5 NS ns1.dns.sa.
dns.sa. 5 NS ns3.dns.sa.
dns.sa. 5 NS ns2.dns.sa.
Authority
The response has no authority records.
Additional
ns1.dns.sa. 5 A 86.111.195.3
ns2.dns.sa. 5 A 86.111.196.3
ns3.dns.sa. 5 A 194.58.198.32
ns1.dns.sa. 5 AAAA 2001:67c:18c8:10:0:0:0:3
ns2.dns.sa. 5 AAAA 2001:67c:130:10:0:0:0:3
ns3.dns.sa. 5 AAAA 2a01:3f1:3032:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0