Reverse DNS Lookup
Enter an IP address or a domain name. The tool finds the reverse DNS (PTR) name for each address and checks whether that name points back to the same address.
- DNS
- Live check
- Free, no sign-up
- Results are not published
Run Reverse DNS
At a glance
- What it checks
- Look up PTR records for an IP address or a domain's addresses and confirm they resolve forward again.
- Data source
- PTR records in the in-addr.arpa / ip6.arpa zones via public resolvers.
- Freshness
- Live check; results are cached for up to 5 minutes
- Limits
- PTR records are set by whoever controls the IP block, usually the hosting provider, not the domain owner. Methodology
- Cost
- Free, no account needed
Understanding the result
How reverse DNS works
Forward DNS maps names to addresses. Reverse DNS goes the other way, using special zones under in-addr.arpa for IPv4 and ip6.arpa for IPv6. The address 192.0.2.10, for example, is looked up as 10.2.0.192.in-addr.arpa. The PTR record at that name holds the hostname.
Reverse zones are controlled by whoever holds the IP address block, which is usually your hosting provider or ISP, not by the owner of the domain. That is why you often cannot set a PTR record in the same place as your other DNS records.
What the tool checks
When you enter a domain, the tool first resolves its A and AAAA records and checks up to six of the resulting addresses. When you enter an IP address, only that address is checked.
For each address it shows the reverse name that was queried, up to three PTR hostnames, and whether the address is public or falls in a private or reserved range. It then performs a forward-confirmed reverse DNS (FCrDNS) check: each PTR hostname is resolved forward, and the check succeeds if one of them returns the original address.
Reading the findings
- PTR PASS: every address has a PTR record.
- PTR WARNING: some addresses have a PTR record and others do not.
- PTR INFO: none of the addresses has a PTR record. This is common for web servers and CDN addresses and usually harmless.
- FCrDNS PASS: every PTR name resolves back to its address.
- FCrDNS WARNING: at least one PTR name does not resolve back, which some receiving mail servers treat as a sign of a poorly configured or compromised sender.
Why it matters for email
Reverse DNS is optional for most services, but it matters for servers that send email. Many receiving systems check that the sending IP has a PTR record and that it forward-confirms, and some reject or penalize mail when it does not. If you run your own outgoing mail server at 203.0.113.25, ask your provider to set its PTR to a hostname such as mail.example.com, and make sure mail.example.com has an A record pointing to 203.0.113.25.
Pair this check with the MX Checker for incoming mail and the Email Security Checker for SPF and DMARC. To see who holds an address block, use the IP Lookup.
Frequently asked questions
How do I change my PTR record?
Ask whoever assigned you the IP address, usually your hosting provider, cloud platform or ISP. Many cloud control panels have a reverse DNS setting on each public IP. Your domain registrar cannot change it.
Does my website need reverse DNS?
No. Browsers do not check PTR records. Reverse DNS mostly matters for mail servers and for making logs and network diagnostics easier to read.
Can an IP address have more than one PTR record?
Technically yes, but it is discouraged because many systems only read the first one. The tool shows up to three PTR names per address.
Why does a private IP address have no PTR record?
Private and reserved ranges such as 10.0.0.0/8 are not routed on the internet, and their reverse zones are not published in public DNS. The tool labels such addresses with their scope so you can see why no PTR was found.