flowmon.voiceworks.nl has no CNAME records.
Question and response
Question
dig flowmon.voiceworks.nl. NS
Answer
The response has no answer records.
Authority
voiceworks.nl. 618 SOA liz.ns.cloudflare.com. dns.cloudflare.com. 2397413908 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0