While DNS records refer a domain name to the IP address where the the website is hosted, there is also rDNS (reverse DNS) and specifically PTR (pointer) records which do the reverse: link a server's IP to a domain name. This is important for many things, but especially email. Many email servers require that other servers that send them mail have PTR records to prevent spam. Setting your PTR Record DNS settings are set with your registrar, while rDNS settings are set with your server or VPS pr...
