Apex domains cannot have CNAME records.
Question and response
Question
dig outbound.lightedge.com. NS
Answer
outbound.lightedge.com. 4 NS ns2.gslb.lightedge.com.
outbound.lightedge.com. 4 NS ns1.gslb.lightedge.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0