dns4.itoolabs.net has no CNAME records.
Question and response
Question
dig dns4.itoolabs.net. NS
Answer
The response has no answer records.
Authority
itoolabs.net. 91 SOA ns.itoolabs.com. hostmaster.itoolabs.com. 2026011201 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0