Reverse DNS(rDNS) or regularly referred to as a PTR record, works oppositely of the Domany Name System. Instead of converting domain names to IP addresses, it turns the IP address into a hostname. The purpose of the PTR record is to prove that a particular domain uses this specific IP address. Some mail service providers demand that your server's IP has a Reverse DNS record, which corresponds to your hostname, otherwise, it will not accept emails from your server or will flag any message sent from there as spam.
HostArmada servers fully support these types of records. You may configure them on our VPS and Dedicated Servers, as these products have a dedicated IP address, and you are the only user. To have this record set for your server, please log into your Client Area. From there, submit a support ticket in the "Domains and DNS" category.