dev.tagadab.com has no CNAME records.
Question and response
Question
dig dev.tagadab.com. NS
Answer
The response has no answer records.
Authority
tagadab.com. 571 SOA ns01.tagadab.com. hostmaster.tagadab.com. 2020022349 3600 600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0