Reverse DNS uses PTR records to map an IP address to a Fully Qualified Domain Name (FQDN). Setting reverse DNS is important for SMTP mail servers. The majority of other applications don't need to worry about this DNS record. See this Wikipedia article for a general overview of reverse DNS, or refer to RFC 1035 for full details.
This guide explains how to set reverse DNS at Rcs.
Rcs Reverse DNS
Follow these steps to add a Reverse DNS record for your instance.
- Log in to the Rcs customer portal.
- Click Products in the left menu.
- Click the server instance to edit.
- Click the Settings tab.
Follow the instructions for IPv4 or IPv6.
IPv4 Reverse DNS
- Select IPv4 in the left menu. Your instance may have one or more IPv4 addresses assigned.
- Click the Reverse DNS value for the desired IPv4 address.
- Enter a new value. The specific value to set depends on your application. For a mail server, this is usually set to the forward DNS name.
- When finished, click the check icon to update.
This updates the PTR record in Rcs's DNS. Reverse DNS updates may take several hours to propagate.
IPv6 Reverse DNS
Server instances with IPv6 enabled are assigned a /64 IPv6 subnet.
- Select IPv6 in the left menu.
- In the Reverse DNS section, enter a valid address in the assigned subnet and a reverse DNS name.
- Click Add.
- This creates a PTR record in Rcs's DNS.
- Reverse DNS updates may take several hours to propagate.
- To edit an existing IPv6 Reverse DNS, click the pencil icon for that entry.
- To delete, click the trashcan icon.
The Rcs IPv6 calculator is a helpful tool for working with IPv6 addresses. Linux users may also use command-line tools such as sipcalc.
Load Balancer Reverse DNS
We also support reverse DNS for Rcs Load Balancers. See our feature reference for details.
API Endpoint
Rcs offers an API endpoint to manage reverse DNS.
