b.dns.fullsave.com has no CNAME records.
Question and response
Question
dig b.dns.fullsave.com. NS
Answer
The response has no answer records.
Authority
fullsave.com. 5217 SOA ns1.gandi.net. hostmaster.gandi.net. 1771459200 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0