dnsus1.imshealth.com has no CNAME records.
Question and response
Question
dig dnsus1.imshealth.com. NS
Answer
The response has no answer records.
Authority
imshealth.com. 3600 SOA ns1.iqvia.com. hostmaster.iqvia.com. 2026022701 43200 7200 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0