Find the host name of an IP address and check that it points back (FCrDNS)
Runs in your browser. Only the lookup you start is sent to cloudflare-dns.com or dns.google; nothing else leaves your device. Updated on 18 Oct 2026.A reverse DNS lookup turns an IP address into a host name by asking for its PTR record. The check then looks that name up again, and if 1 of its addresses is the original IP, the name is forward-confirmed. Mail servers rely on that second step, because anyone can set a PTR.
Type an IPv4 or IPv6 address, such as 8.8.8.8, in IP address (IPv4 or IPv6).
Press Look up to fetch the PTR record and then the addresses of the name it returns.
Read the PTR name and the Points back? column: Yes means forward-confirmed reverse DNS passes.
Press Copy result to copy the host name and the verdict.
Type an IPv4 or IPv6 address and this reverse DNS lookup asks a public resolver for its PTR record. The question goes to a special name built from the address: 8.8.8.8 becomes 8.8.8.8.in-addr.arpa (the four numbers reversed), and an IPv6 address becomes 32 hex digits reversed under ip6.arpa. The page builds that name for you and shows it.
A PTR record on its own proves little. Whoever controls an address block can put any name in it, including a name they do not own. So the page takes each name the PTR returns and looks up its A record (or AAAA for IPv6). If one of those addresses is the IP you started with, the result is forward-confirmed reverse DNS, also called FCrDNS or the "iprev" check in RFC 8601. That is the test many mail servers apply before accepting a message, and a missing or unconfirmed reverse name is one of the commonest reasons a new mail server lands in spam.
When there is no PTR at all, the page says so. That is normal for home connections and many cloud addresses. The reverse name is set by whoever holds the address block, usually your hosting or internet provider, not in your own domain's DNS, so a fix means asking them or using their control panel.
The IP you type is sent to the resolver you choose, Cloudflare or Google, to answer it; nothing else leaves your device. The tool does not find other websites hosted on the same IP (the other meaning of "reverse IP lookup"), and it does not show who owns the address; the ASN Lookup names the network that announces it.
Type the IP address. The page builds its reverse name, such as 8.8.8.8.in-addr.arpa, asks a public resolver for the PTR record there, and shows the name it holds. For 8.8.8.8 the answer is dns.google. Both IPv4 and IPv6 addresses work.
Forward-confirmed reverse DNS means the IP's PTR name, looked up again, returns that same IP. A PTR alone can claim any name, but only the owner of a name can make it point back. Mail servers use this check, called iprev in RFC 8601, to judge whether a sender is who it claims.
PTR records are set by whoever holds the address block, usually the internet or hosting provider, not in your domain's own DNS. Home connections and many cloud servers have none or a generic one. Ask the provider, or look for a reverse DNS setting in its control panel.
Many receiving mail servers reject or down-rank mail from an address with no PTR record, or with a PTR that does not resolve back. A mail server should have a PTR naming a host whose own A or AAAA record is that same IP, which is exactly the pair of lookups this page makes.
Only to the resolver you choose, Cloudflare at cloudflare-dns.com or Google at dns.google, as the reverse name it needs to answer. The lookup runs from your browser. This site never receives the address, and nothing else about you leaves your device.
Still stuck? Ask about Reverse DNS Lookup and anybody who knows can answer. No account needed.
Also works as: PTR Record Lookup.
Same job, other tools: AAAA Record Lookup (IPv6) – Check whether a domain has an IPv6 address, and what it is · CAA Record Lookup – See which certificate authorities a domain allows to issue its SSL certificates · Open Port Checker – See if a port forwarded on your router is reachable from the internet · AS Number Lookup – Turn an AS number into the network name, registry and allocation date · IP to ASN Lookup – Map an IP address to the ASN that announces it, with the BGP prefix · DNSKEY Lookup – List a zone’s DNSKEY records with key tags, KSK or ZSK roles, algorithms and key sizes.