b.planeetta.net has no CNAME records.
Question and response
Question
dig b.planeetta.net. NS
Answer
The response has no answer records.
Authority
planeetta.net. 1421 SOA a.planeetta.net. dns.cloudflare.com. 2395803566 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0