Apex domains cannot have CNAME records.
Question and response
Question
dig wireless.csail.mit.edu. NS
Answer
wireless.csail.mit.edu. 5 NS auth-ns1.csail.mit.edu.
wireless.csail.mit.edu. 5 NS auth-ns3.csail.mit.edu.
wireless.csail.mit.edu. 5 NS auth-ns0.csail.mit.edu.
wireless.csail.mit.edu. 5 NS auth-ns2.csail.mit.edu.
Authority
The response has no authority records.
Additional
auth-ns0.csail.mit.edu. 4 A 128.30.2.123
auth-ns1.csail.mit.edu. 4 A 128.31.0.18
auth-ns2.csail.mit.edu. 4 A 128.52.32.80
auth-ns3.csail.mit.edu. 4 A 18.220.24.142
auth-ns0.csail.mit.edu. 4 AAAA 2603:400a:0:7d2:0:0:801e:27b
auth-ns3.csail.mit.edu. 4 AAAA 2600:1f16:ceb:1302:0:0:0:a
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0