How to Use a PTR Record for Reverse DNS in 2025
Published: 17 Jun, 2025

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Reverse DNS (rDNS) is a critical part of internet infrastructure, especially when it comes to email delivery, server verification, and cybersecurity. At the heart of reverse DNS is the PTR record—short for Pointer Record. While most people are familiar with A records (which map domain names to IP addresses), the PTR record does the reverse: it maps an IP address back to a domain name.

In this guide, we’ll explore what PTR records are, how they function, why they matter in 2025, and how to set them up properly.

What Is a PTR Record?

A PTR (Pointer) record is a type of DNS record used to perform reverse DNS lookups. Instead of resolving a domain name to an IP address (like an A or AAAA record), it resolves an IP address to a domain name. This is especially important in verifying servers—particularly email servers—to reduce the risk of spam and phishing.

For example, if a mail server at IP address 192.0.2.10 sends an email claiming to be from example.com, the receiving server may perform a reverse DNS lookup. If the PTR record for that IP points to mail.example.com, and the forward lookup of mail.example.com also returns 192.0.2.10, the server can confirm the match and accept the mail.

Why PTR Records Matter in 2025

In the modern digital environment, security and authenticity are more crucial than ever. Here's why PTR records are still relevant:

  • Email deliverability: Mail servers often reject or mark as spam any message coming from an IP without a valid PTR record.

  • Network trust: Reverse DNS is part of many firewalls and monitoring systems to validate traffic sources.

  • Compliance: Some enterprise and cloud systems require rDNS for operational compliance.

  • Troubleshooting: Identifying servers by domain instead of just raw IPs helps in debugging and tracing issues.

How Reverse DNS Works with PTR Records

The process of reverse DNS is a bit different from standard DNS:

  1. The IP address is reversed.

  2. A .in-addr.arpa (for IPv4) or .ip6.arpa (for IPv6) suffix is appended.

  3. A DNS query is made for the PTR record of that reversed address.

  4. If a PTR record exists, it returns the associated domain name.

So, for IP 192.0.2.10, the reverse lookup query becomes:
10.2.0.192.in-addr.arpa

If the PTR record exists, the DNS server might return:
mail.example.com.

How to Set Up a PTR Record in 2025

Setting up a PTR record is a bit different from setting up other DNS records because it must be done by the owner of the IP address—typically your hosting provider, ISP, or cloud provider.

Here’s how to proceed:

  1. Check Your IP Ownership: Confirm whether you're using a static IP and whether your hosting provider allows reverse DNS configuration.

  2. Access Hosting Panel or Contact Support: Some control panels allow direct PTR management, while others require submitting a support ticket.

  3. Request or Set the PTR: Provide the IP address and the domain name it should point to. Ensure that forward DNS (A record) for the domain also points back to the IP.

  4. Test the Setup: After propagation (which may take a few hours), use tools like dig -x or online reverse DNS lookup services to confirm.

Best Practices for PTR Records

While setting up PTR records is generally straightforward, following these practices can help you avoid issues:

  • Make sure the hostname returned by the PTR record matches the domain used in your server’s SMTP greeting if you're running a mail server.

  • Always ensure forward and reverse DNS match. Mismatched records often trigger spam filters.

  • Use FQDNs (Fully Qualified Domain Names) in PTR records—no short names or aliases.

  • Test regularly to ensure nothing has broken after DNS or server changes.

Conclusion

PTR records and reverse DNS aren’t flashy, but they’re essential for trust on the internet. Whether you're running a web server, managing outbound email, or configuring cloud infrastructure, setting up reverse DNS properly is a must in 2025. If you rely on clean server reputation and good deliverability, ignoring PTR records could cost you visibility and trust.

FAQs

1. Can I set up a PTR record for a dynamic IP?
No, PTR records generally require a static IP address. Dynamic IPs can change frequently and aren't ideal for reverse DNS.

2. How do I test a PTR record?
Use dig -x from the command line or an online reverse DNS lookup tool. It should return the domain name mapped to the IP.

3. Why does my mail go to spam even with a PTR record?
A PTR record alone isn’t enough. SPF, DKIM, and DMARC also need to be configured. Also, ensure your domain isn’t blacklisted.

4. Can I set multiple PTR records for one IP?
Technically possible, but not recommended. Most applications (like email) expect only one PTR record per IP.

5. Who controls the PTR records?
The owner of the IP address controls PTR records. If you lease the IP from a hosting company, they manage reverse DNS on your behalf.