Apex domains cannot have CNAME records.
Question and response
Question
dig root-servers.org. NS
Answer
root-servers.org. 5 NS ns-ext.isc.org.
root-servers.org. 5 NS ns.maxgigapop.net.
root-servers.org. 5 NS nnp.netnod.se.
root-servers.org. 5 NS a.icann-servers.net.
root-servers.org. 5 NS sec2.authdns.ripe.net.
root-servers.org. 5 NS jokulsa.asbyrgi.net.
Authority
The response has no authority records.
Additional
a.icann-servers.net. 5 A 199.43.135.53
nnp.netnod.se. 5 A 194.58.198.133
a.icann-servers.net. 5 AAAA 2001:500:8f:0:0:0:0:53
nnp.netnod.se. 5 AAAA 2a01:3f1:3033:8000:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0