Apex domains cannot have CNAME records.
Question and response
Question
dig san.attens.net. NS
Answer
san.attens.net. 5 NS ns-west.cerf.net.
san.attens.net. 5 NS ns-east.cerf.net.
Authority
The response has no authority records.
Additional
ns-east.cerf.net. 5 A 99.99.99.136
ns-west.cerf.net. 5 A 68.94.156.136
ns-east.cerf.net. 2 AAAA 2001:1890:1ff:9f1:99:99:99:136
ns-west.cerf.net. 2 AAAA 2001:1890:1ff:9f0:68:94:156:136
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0