_spf2.tuthost.com has no CNAME records.
Question and response
Question
dig _spf2.tuthost.com. NS
Answer
The response has no answer records.
Authority
tuthost.com. 3164 SOA ns1.tuthost.com. hostmaster.tuthost.com. 2025012000 3600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0