What is Reverse DNS?

Reverse DNS (rDNS) is the process of resolving an IP address back to a hostname. While standard DNS maps domain names to IP addresses, reverse DNS does the opposite by looking up PTR (Pointer) records in the in-addr.arpa zone.

How It Works

To perform a reverse lookup, the IP address octets are reversed and appended with .in-addr.arpa. For example, looking up 8.8.8.8 queries the PTR record at:

8.8.8.8.in-addr.arpa. IN PTR dns.google.

Why PTR Records Matter

Email Deliverability — Many mail servers reject email from IPs without valid PTR records. A matching reverse DNS entry helps prove the server is legitimate.
Security and Logging — Reverse DNS helps identify the source of network connections in server logs and security audits.
Anti-Spam Checks — Spam filters often verify that the sending IP has a PTR record that resolves back to the same IP (forward-confirmed reverse DNS).
Network Troubleshooting — Reverse lookups help identify which servers or services are associated with specific IP addresses.

Who Sets PTR Records?

PTR records are managed by the owner of the IP address block, typically your hosting provider or ISP. You usually need to request PTR record changes through their control panel or support team.

What reverse DNS (PTR) shows

Reverse DNS maps an IP address back to a hostname using a PTR record. Normal DNS answers "what IP does this name use?"; reverse DNS answers the opposite. This tool asks Google Public DNS for the PTR record of an IP address.

Why it matters

Email deliverability. Many receiving mail servers expect the sending IP to have a PTR record, and that the hostname it returns points back to the same IP. Without it, mail is more likely to be rejected or marked as spam.
Logs and diagnostics. Hostnames make server logs and network traces much easier to read.

Who controls it

PTR records are not stored in your domain's DNS zone. They are controlled by whoever owns the IP address, which is usually your hosting provider or internet service provider. To change one, ask them or use the reverse-DNS setting in their control panel.

Reading the result

A hostname means a PTR record exists. For mail servers, it should match your mail hostname.
No record is common for ordinary home connections.

To see who owns an address, use the IP lookup. See also our reverse DNS lookup guide.

Reverse DNS Lookup