_spf.sui-inter.net has no CNAME records.
Question and response
Question
dig _spf.sui-inter.net. NS
Answer
The response has no answer records.
Authority
sui-inter.net. 9 SOA ch.pro.io. hostmaster.sui-inter.net. 2026020512 10800 3600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0