smtp2.crgroup.com has no NS records.
NS records for this zone are defined at crgroup.com.
NS records for this zone are defined at crgroup.com.
Question and response
Question
dig smtp2.crgroup.com. NS
Answer
The response has no answer records.
Authority
crgroup.com. 300 SOA ns1-02.azure-dns.com. zone.easydns.com. 1748125764 3600 600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0