64-33-220-68.pingtone.net has no NS records.
NS records for this zone are defined at pingtone.net.
NS records for this zone are defined at pingtone.net.
Question and response
Question
dig 64-33-220-68.pingtone.net. NS
Answer
The response has no answer records.
Authority
pingtone.net. 900 SOA ns.pingtone.net. dnsmaster.pingtone.com. 1705954185 10800 3600 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0