smtp-aps00.hosted.exlibrisgroup.com has no CNAME records.
Question and response
Question
dig smtp-aps00.hosted.exlibrisgroup.com. NS
Answer
The response has no answer records.
Authority
hosted.exlibrisgroup.com. 5458 SOA ns0-mnm-ol8.dc04. hostmaster.hosted.exlibrisgroup.com. 2024111991 28800 7200 604800 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0