rb-techdiff-mgmt.rb.atl.efscloud.net has no CNAME records.
Question and response
Question
dig rb-techdiff-mgmt.rb.atl.efscloud.net. NS
Answer
The response has no answer records.
Authority
rb.atl.efscloud.net. 537 SOA ns1.efscloud.net. root.efscloud.net. 1652131484 7200 900 3600000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0