ftp.conventioncalendar.com has no NS records.
NS records for this zone are defined at conventioncalendar.com.
NS records for this zone are defined at conventioncalendar.com.
Question and response
Question
dig ftp.conventioncalendar.com. NS
Answer
The response has no answer records.
Authority
conventioncalendar.com. 86400 SOA dns1.swiftrfp.net. admin.swiftrfp.net. 2023011256 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0