spf2.vodafone.com has no NS records.
NS records for this zone are defined at vodafone.com.
NS records for this zone are defined at vodafone.com.
Question and response
Question
dig spf2.vodafone.com. NS
Answer
The response has no answer records.
Authority
vodafone.com. 900 SOA ns1.vodafone.com. hostmaster.vodafone.com. 2008109942 28800 7200 604800 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0