ns-admin.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 ns-admin.vodafone.com. NS
Answer
The response has no answer records.
Authority
vodafone.com. 900 SOA ns1.vodafone.com. hostmaster.vodafone.com. 2008109923 28800 7200 604800 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0