Apex domains cannot have CNAME records.
Question and response
Question
dig credit-suisse.com. NS
Answer
credit-suisse.com. 5 NS mercury.ubs.com.
credit-suisse.com. 5 NS uranus.ubs.com.
credit-suisse.com. 5 NS a2-65.akam.net.
credit-suisse.com. 5 NS a3-64.akam.net.
credit-suisse.com. 5 NS a5-65.akam.net.
credit-suisse.com. 5 NS a1-12.akam.net.
credit-suisse.com. 5 NS a26-66.akam.net.
credit-suisse.com. 5 NS neptune.ubs.com.
credit-suisse.com. 5 NS a28-65.akam.net.
credit-suisse.com. 5 NS jupiter.ubs.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0