Apex domains cannot have CNAME records.
Question and response
Question
dig safeservedns.com. NS
Answer
safeservedns.com. 5 NS edns4.registrar-servers.com.
safeservedns.com. 5 NS edns3.registrar-servers.com.
safeservedns.com. 5 NS edns4.ultradns.net.
safeservedns.com. 5 NS edns4.ultradns.biz.
safeservedns.com. 5 NS edns4.ultradns.com.
safeservedns.com. 5 NS edns4.ultradns.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0