Apex domains cannot have CNAME records.
Question and response
Question
dig verio.com. NS
Answer
verio.com. 5 NS ns2.verio.com.
verio.com. 5 NS ns1.verio.com.
Authority
The response has no authority records.
Additional
ns1.verio.com. 5 A 66.96.142.149
ns2.verio.com. 5 A 65.254.254.161
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0