engtools.sys.cogentco.com has no CNAME records.
Question and response
Question
dig engtools.sys.cogentco.com. NS
Answer
The response has no answer records.
Authority
sys.cogentco.com. 10581 SOA auth1.dns.cogentco.com. dns.cogentco.com. 2026022500 10800 3600 604800 43200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0