mailadmin.aciglobal.com has no CNAME records.
Question and response
Question
dig mailadmin.aciglobal.com. NS
Answer
The response has no answer records.
Authority
aciglobal.com. 59 SOA ns1.aciglobal.com. hostmaster.aciglobal.com. 2026012901 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0