Apex domains cannot have CNAME records.
Question and response
Question
dig postdocrecruiting.com. NS
Answer
postdocrecruiting.com. 2 NS ns2.postdocrecruiting.com.
postdocrecruiting.com. 2 NS ns1.postdocrecruiting.com.
Authority
The response has no authority records.
Additional
ns1.postdocrecruiting.com. 2 A 61.97.247.28
ns2.postdocrecruiting.com. 2 A 61.97.247.55
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0