Reverse DNS links an IP address back to a domain name using PTR records. This guide explains what reverse DNS is, why it matters, how to test it, and how to request configuration for your services.
What Is Reverse DNS
Reverse DNS lookups resolve an IP address to a domain name. This is the opposite of forward DNS, which resolves a domain name to an IP address.
Forward DNS uses A records to map names to addresses. Reverse DNS uses PTR records to map addresses back to names.
Reverse DNS is commonly used by mail servers and security systems to validate the identity of sending hosts.
Why Reverse DNS Matters
Many external mail servers require a valid PTR record as part of their anti spam checks. If a sending IP does not have reverse DNS configured, email delivery may fail.
Typical symptoms include rejected messages or SMTP errors indicating that reverse DNS is missing or invalid.
Configuring reverse DNS improves mail deliverability and helps establish trust with receiving servers.
Testing Reverse DNS
You can test whether an IP address has a PTR record by performing a reverse lookup.
From a server with SSH access, run a reverse DNS query using standard DNS tools and replace the address with the IP you want to test.
If a PTR record exists, the result will show the domain name associated with the IP address.
If no record is returned, reverse DNS is not configured for that address.
Configuring Reverse DNS for Your Services
Reverse DNS configuration depends on the type of service and IP ownership.
VPS and Dedicated Servers
If you are using a VPS or a dedicated server, reverse DNS can be configured on request. Submit a request that includes the IP address and the domain name that should be associated with it.
Requests can be submitted through the Système de tickets d'assistance.
Shared and Reseller Hosting
Shared and reseller services typically have reverse DNS configured on the main server IP.
If you are using a dedicated IP and reverse DNS is not set as expected, you can request configuration by providing your domain name and IP address.
Managing DNS and Domains
While PTR records are managed at the IP level, overall DNS and domain settings can be reviewed through the Colonelserver Domaine services.
Account level details and service information are available in the Espace Client.
Obtenir de l'aide
If you are unsure whether reverse DNS is required for your setup or need assistance validating configuration, contact the technical team for guidance.
Proper reverse DNS configuration is an important step for reliable email delivery and server reputation.