Definition
PTR records are the opposite of A records: they map an IP address to a hostname. Used for reverse DNS lookups. Mail servers often check PTR records to verify the sending IP has valid reverse DNS — missing PTR records are a spam signal. PTR records are managed by whoever owns the IP block (typically your hosting provider or ISP), not by your domain registrar.
Use the tool: Reverse DNS Lookup — check ptr record for any domain.