_netblocks2.singlehop.com has no CNAME records.
Question and response
Question
dig _netblocks2.singlehop.com. NS
Answer
The response has no answer records.
Authority
singlehop.com. 10211 SOA ns1.singlehop.com. netops.singlehop.com. 2008071001 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0