spf.sg.de.o2.com has no NS records.
NS records for this zone are defined at sg.de.o2.com.
NS records for this zone are defined at sg.de.o2.com.
Question and response
Question
dig spf.sg.de.o2.com. NS
Answer
The response has no answer records.
Authority
sg.de.o2.com. 600 SOA ns1.o2online.de. domain-de.o2.com. 2026010200 21600 3600 604800 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0