Apex domains cannot have CNAME records.
Question and response
Question
dig houstonprocurement.com. NS
Answer
houstonprocurement.com. 5 NS ns-802.awsdns-36.net.
houstonprocurement.com. 5 NS ns-1760.awsdns-28.co.uk.
houstonprocurement.com. 5 NS ns-1064.awsdns-05.org.
houstonprocurement.com. 5 NS ns-1807.awsdns-33.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0