Apex domains cannot have CNAME records.
Question and response
Question
dig registry.om. NS
Answer
registry.om. 5 NS ns1.registry.om.
registry.om. 5 NS cctld.beta.aridns.net.au.
registry.om. 5 NS cctld.delta.aridns.net.au.
registry.om. 5 NS cctld.alpha.aridns.net.au.
registry.om. 5 NS ns2.registry.om.
registry.om. 5 NS cctld.gamma.aridns.net.au.
Authority
The response has no authority records.
Additional
ns1.registry.om. 71210 A 185.27.88.50
ns2.registry.om. 71210 A 185.27.89.50
ns1.registry.om. 71210 AAAA 2a00:9120:1:0:0:0:0:50
ns2.registry.om. 71210 AAAA 2a00:9120:2:0:0:0:0:50
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0