Apex domains cannot have CNAME records.
Question and response
Question
dig webmasterplus.us. NS
Answer
webmasterplus.us. 1 NS ns-1312.awsdns-36.org.
webmasterplus.us. 1 NS ns-410.awsdns-51.com.
webmasterplus.us. 1 NS ns-320.awsdns-40.com.
webmasterplus.us. 1 NS ns-556.awsdns-05.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0