o18.ptr4232.mediaslide.com has no CNAME records.
Question and response
Question
dig o18.ptr4232.mediaslide.com. NS
Answer
The response has no answer records.
Authority
mediaslide.com. 300 SOA ns-cloud-b1.googledomains.com. dns-admin.google.com. 2 21600 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0