ns1.proofpoint.us has no NS records.
NS records for this zone are defined at proofpoint.us.
NS records for this zone are defined at proofpoint.us.
Question and response
Question
dig ns1.proofpoint.us. NS
Answer
The response has no answer records.
Authority
proofpoint.us. 60 SOA ns1.proofpoint.com. ops.proofpoint.com. 2017042218 28800 2880 604800 1200
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0