ns100.sentris.com has no CNAME records.
Question and response
Question
dig ns100.sentris.com. NS
Answer
The response has no answer records.
Authority
sentris.com. 9573 SOA ns100.sentris.com. hostmaster.sentris.com. 2020062913 14400 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0