Apex domains cannot have CNAME records.
Question and response
Question
dig it-prod-cots.aws.umd.edu. NS
Answer
it-prod-cots.aws.umd.edu. 5 NS ns-1554.awsdns-02.co.uk.
it-prod-cots.aws.umd.edu. 5 NS ns-470.awsdns-58.com.
it-prod-cots.aws.umd.edu. 5 NS ns-648.awsdns-17.net.
it-prod-cots.aws.umd.edu. 5 NS ns-1531.awsdns-63.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0