authmail1.symauth.com has no NS records.
NS records for this zone are defined at symauth.com.
NS records for this zone are defined at symauth.com.
Question and response
Question
dig authmail1.symauth.com. NS
Answer
The response has no answer records.
Authority
symauth.com. 180 SOA ns20.digicertdns.com. dns.digicertdns.com. 2009010139 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0