mail01.keepit.com has no CNAME records.
Question and response
Question
dig mail01.keepit.com. NS
Answer
The response has no answer records.
Authority
keepit.com. 10659 SOA pns41.cloudns.net. hostmaster.keepit.com. 2026022349 43200 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0