Apex domains cannot have CNAME records.
Question and response
Question
dig co.il. NS
Answer
co.il. 5 NS lookup.iucc.ac.il.
co.il. 5 NS ns3.ns.il.
co.il. 5 NS nse.ns.il.
co.il. 5 NS ilns.ilan.net.il.
co.il. 5 NS ns1.ns.il.
co.il. 5 NS ns4.ns.il.
co.il. 5 NS nsb.ns.il.
co.il. 5 NS nsa.ns.il.
Authority
The response has no authority records.
Additional
ns1.ns.il. 147121 A 194.146.106.122
ns3.ns.il. 115760 A 194.0.11.103
ns4.ns.il. 75580 A 204.61.216.134
nsa.ns.il. 40959 A 192.115.7.53
nsb.ns.il. 15603 A 192.115.7.60
nse.ns.il. 98678 A 192.115.4.235
ilns.ilan.net.il. 24511 A 128.139.35.5
ns1.ns.il. 147121 AAAA 2001:67c:1010:31:0:0:0:53
ns3.ns.il. 115760 AAAA 2001:678:e:103:0:0:0:53
ns4.ns.il. 75580 AAAA 2001:500:14:6134:ad:0:0:1
nsa.ns.il. 40959 AAAA 2a01:4280:7:0:0:0:0:53
nsb.ns.il. 15603 AAAA 2a01:4280:7:0:0:0:0:60
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0