dns4.ptd.net has no CNAME records.
Question and response
Question
dig dns4.ptd.net. NS
Answer
The response has no answer records.
Authority
ptd.net. 3179 SOA dns1.ptd.net. etoybrg.corp.ptd.net. 2025062501 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0