master.dns.rcn.net has no CNAME records.
Question and response
Question
dig master.dns.rcn.net. NS
Answer
The response has no answer records.
Authority
dns.rcn.net. 4860 SOA master.dns.rcn.net. hostmaster.rcn.com. 2025080801 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0