smtp.pgckz.com has no NS records.
NS records for this zone are defined at pgckz.com.
NS records for this zone are defined at pgckz.com.
Question and response
Question
dig smtp.pgckz.com. NS
Answer
The response has no answer records.
Authority
pgckz.com. 600 SOA a.share-dns.com. master.share-dns.com. 1770702378 3600 1200 86400 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0