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Reverse DNS Lookup

Enter an IPv4 or IPv6 address: the tool builds the in-addr.arpa or ip6.arpa name, fetches the PTR record, and shows which network the address is registered to.

Your browser queries these services directly, so the name you look up and your IP address are visible to them: Cloudflare DNS and Google Public DNS (both public recursive resolvers) for records and comparison, and rdap.org, a redirector that forwards to the registry's RDAP server, for registration data. DevDome does not proxy, see or store these lookups. Privacy policy.

Run a lookup to get an evidence-based summary: web resolution, delegation, DNSSEC, email records, CAA and expiration, each with the observation behind it.
Enter a name above to query common DNS records (A, AAAA, CNAME, MX, TXT, NS, SOA, CAA) from a public recursive resolver, or pick a specific type including DS, DNSKEY, SRV, TLSA, SVCB and HTTPS.
Registration data appears here via RDAP: registrar, creation and expiration dates, EPP status codes, nameservers and DNSSEC delegation state.
SPF and DMARC analysis appears here: record syntax, the 10-DNS-lookup limit, policy strength and common misconfigurations, with the exact records as evidence.
Compares one record type between Cloudflare and Google. These are observations from two public recursive resolvers, not proof of global propagation. Add an expected value above to check whether your change is visible to each.

The lookup nobody can type by hand

Reverse DNS is a normal DNS query against a very abnormal name: an IPv4 address reversed octet by octet under in-addr.arpa, or an IPv6 address expanded to 32 reversed nibbles under ip6.arpa. This tool accepts the address in any normal form, including compressed IPv6, bracketed addresses with ports, and addresses with embedded IPv4 tails, builds the query name for you and shows it, so you can reuse it in dig or logs.

The most common reason to care is outbound email: sending IPs without a PTR that forward-confirms are penalized or refused by many receivers. The second is log forensics: a PTR plus the RDAP network registration turns an anonymous IP in your access logs into "a Hetzner server" or "a Comcast residential line", which changes how you read the traffic. DevDome's bot protection does this classification automatically for your site.

See which networks are hitting your site →

Reverse DNS FAQ

What is a PTR record and who controls it?

A PTR record maps an IP address back to a hostname, the reverse of an A or AAAA record. Crucially, it lives in the address space of whoever owns the IP range, not in your domain’s zone: for most servers that means your hosting provider or cloud vendor sets it, usually through a control panel field called reverse DNS or PTR. You cannot create a PTR by editing your own domain’s DNS.

How does reverse DNS work for IPv6?

The same PTR mechanism, but the name is built by expanding the address to all 32 hexadecimal digits, reversing them, and appending ip6.arpa, which produces names like 1.0.0.0....8.b.d.0.1.0.0.2.ip6.arpa. Nobody writes those by hand: paste any IPv6 address above, in compressed form like 2001:db8::1, and the tool expands and reverses it for you.

Does a missing PTR record hurt email delivery?

For a server that sends mail, yes: many receiving servers treat a connecting IP with no PTR, or a PTR that does not match the HELO hostname, as a spam signal, and some reject outright. For an IP that does not send mail, a missing PTR is normal and harmless: most consumer and cloud IPs have either no PTR or a generic provider-assigned one.

What is forward-confirmed reverse DNS (FCrDNS)?

The two-way check mail servers actually use: resolve the IP to a hostname via PTR, then resolve that hostname back to an IP via A or AAAA, and require the original IP to appear in the answer. A PTR pointing at a name that does not resolve back proves nothing. After looking up your PTR here, run the returned hostname through the DNS lookup to confirm the round trip.

What does the Registration tab show for an IP?

Network registration data over RDAP from the regional internet registry: the network name and handle, the address range the IP belongs to, and the registering country. That tells you which provider is responsible for the address, which is the organization to contact about its PTR record or abuse.

More free tools: DNS & WHOIS Lookup · MX Lookup · SPF Checker · Bot User-Agent Lookup