_spf.talktalk.net has no CNAME records.
Question and response
Question
dig _spf.talktalk.net. NS
Answer
The response has no answer records.
Authority
talktalk.net. 1200 SOA ds0.opaltelecom.net. noc.opaltelecom.net. 2025040100 1200 120 1728000 1200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0