_spfnet1.singtel.com has no CNAME records.
Question and response
Question
dig _spfnet1.singtel.com. NS
Answer
The response has no answer records.
Authority
singtel.com. 551 SOA dnspri.singnet.com.sg. hostmaster.singnet.com.sg. 2025100969 3600 1800 604800 28800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0