Apex domains cannot have CNAME records.
Question and response
Question
dig MIL. NS
Answer
mil. 1 NS PAC2.NIPR.MIL.
mil. 1 NS EUR2.NIPR.MIL.
mil. 1 NS CON1.NIPR.MIL.
mil. 1 NS EUR1.NIPR.MIL.
mil. 1 NS CON2.NIPR.MIL.
mil. 1 NS PAC1.NIPR.MIL.
Authority
The response has no authority records.
Additional
con1.nipr.mil. 144274 A 199.252.157.234
con2.nipr.mil. 162200 A 199.252.162.234
eur1.nipr.mil. 162200 A 199.252.154.234
eur2.nipr.mil. 150495 A 199.252.143.234
pac1.nipr.mil. 133762 A 199.252.180.234
pac2.nipr.mil. 133762 A 199.252.155.234
con1.nipr.mil. 144274 AAAA 2608:140:c:157:0:0:0:234
con2.nipr.mil. 162200 AAAA 2608:120:c:162:0:0:0:234
eur1.nipr.mil. 162200 AAAA 2608:4122:2:154:0:0:0:234
eur2.nipr.mil. 150495 AAAA 2608:4163:1:143:0:0:0:234
pac1.nipr.mil. 133762 AAAA 2608:c184:1:180:0:0:0:234
pac2.nipr.mil. 133762 AAAA 2608:c144:1:155:0:0:0:234
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0