Apex domains cannot have CNAME records.
Question and response
Question
dig forpsi.us. NS
Answer
forpsi.us. 5 NS ns.forpsi.cz.
forpsi.us. 5 NS ns.forpsi.net.
Authority
The response has no authority records.
Additional
ns.forpsi.cz. 5 A 81.2.209.185
ns.forpsi.net. 5 A 81.2.194.130
ns.forpsi.cz. 5 AAAA 2001:15e8:201:1:0:0:0:d1b9
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0