nb.cloud.network-box.com has no CNAME records.
Question and response
Question
dig nb.cloud.network-box.com. NS
Answer
The response has no answer records.
Authority
cloud.network-box.com. 399 SOA nb.cloud.network-box.com. postmaster.cloud.network-box.com. 2025102800 3600 7200 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0