www.rcn.com has no CNAME records.
Question and response
Question
dig www.rcn.com. NS
Answer
The response has no answer records.
Authority
rcn.com. 29362 SOA master.dns.rcn.net. hostmaster.rcn.com. 2026030601 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0