Apex domains cannot have CNAME records.
Question and response
Question
dig domrobot.com. NS
Answer
domrobot.com. 5 NS ns.domrobot.com.
domrobot.com. 5 NS ns.domrobot.org.
domrobot.com. 5 NS ns.domrobot.net.
Authority
The response has no authority records.
Additional
ns.domrobot.com. 5 A 192.174.68.104
ns.domrobot.net. 5 A 176.97.158.104
ns.domrobot.org. 5 A 45.87.158.53
ns.domrobot.com. 5 AAAA 2001:67c:1bc:0:0:0:0:104
ns.domrobot.net. 5 AAAA 2001:67c:10b8:0:0:0:0:104
ns.domrobot.org. 5 AAAA 2a02:d500:0:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0