mx02.service-now.com has no CNAME records.
Question and response
Question
dig mx02.service-now.com. NS
Answer
The response has no answer records.
Authority
service-now.com. 60 SOA edns140.ultradns.com. root.service-now.com. 5478249 900 1800 31536000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0