A guide explaining how to set up reverse DNS (PTR records) for Vultr instances, which maps IP addresses to hostnames for email server validation and other services.
Reverse DNS (rDNS), also called a PTR record, maps an IP address back to a hostname. Unlike regular DNS, which resolves hostnames to IP addresses using A or AAAA records, reverse DNS does the opposite. This is especially important for email servers, where many mail providers perform reverse lookups as part of their spam and trust checks. Having a properly configured reverse DNS entry increases email deliverability and ensures compliance with best practices.
With Vultr, you can configure custom reverse DNS entries for the public IPv4 and IPv6 addresses assigned to your Compute instances. You can update reverse DNS information directly in the Vultr Customer Portal, or using the Vultr CLI.
When you set a reverse DNS entry, make sure the hostname you enter also resolves forward to the same IP address (forward-confirmed reverse DNS, or FCrDNS). This alignment improves credibility with mail providers and avoids potential delivery issues.