rack02.ydim.com has no CNAME records.
Question and response
Question
dig rack02.ydim.com. NS
Answer
The response has no answer records.
Authority
ydim.com. 10800 SOA rack02.ydim.com. tmporter.ydim.com. 1771710090 3600 3600 1209600 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0