Apex domains cannot have CNAME records.
Question and response
Question
dig washtingtonpost.com. NS
Answer
washtingtonpost.com. 5 NS ns2.washtingtonpost.com.
washtingtonpost.com. 5 NS ns1.washtingtonpost.com.
Authority
The response has no authority records.
Additional
ns1.washtingtonpost.com. 5 A 149.50.96.18
ns2.washtingtonpost.com. 5 A 149.50.99.145
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0