ns1.s433.sureserver.com has no CNAME records.
Question and response
Question
dig ns1.s433.sureserver.com. NS
Answer
The response has no answer records.
Authority
sureserver.com. 492 SOA sgate1.sureserver.com. hostmaster.sureserver.com. 1772123615 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0