b.dns.RIPN.net has no CNAME records.
Question and response
Question
dig b.dns.RIPN.net. NS
Answer
The response has no answer records.
Authority
ripn.net. 226 SOA a.dns.ripn.net. noc-dns.msk-ix.ru. 27013605 14400 3600 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0