Why does it matter that a name points back?

Whoever runs an address's reverse zone can make its PTR record say any name, mail.google.com included. When the name's own forward record points back to the same address, the domain's DNS agrees, which a forged PTR record can't arrange. A false means only the PTR record makes the claim.

How current is a host name?

Each row holds the newest PTR record seen for its address in the last 90 days, and the file is rebuilt weekly.

What can a host name tell us?

Often what an address is: a residential line, a mail server, a cloud instance, and sometimes the city it's in.

The reverse DNS name of every address.

Every IPv4 and IPv6 address that answers a PTR query, with the host name it returns and whether that name points back to the address. The file is rebuilt weekly.

Request evaluation

In the lookup API: hostname, on every plan, free included.

Look up one address free with the reverse DNS lookup.

Real rows, with what each column means.

See documentation →

The schema and metadata are in the docs. It is published as CSVGZ.

ip	domain	forward_confirmed
9.9.9.10	dns10.quad9.net	true
208.67.222.222	dns.sse.cisco.com	true
2001:41d0:b00:f300::2	ns20.ovh.net	true
91.235.192.89	host-91-235-193-89.dolnet.pl	false
24.28.1.1	syn-024-028-001-001.res.spectrum.com

ip_rdns_v1

Entries

1,236,479,428

Refresh

Weekly

CSVGZ

9.49 GB

Download it from your code in one call.

Database API reference →

Every official client fetches the current IP RDNS build to disk, as a link for your own runner or into memory, and checks it against its published checksums.

download()

Streams the current build to a file, which lands only once the whole transfer has arrived, so a failed one never leaves a truncated file behind.

downloadUrl()

The time-limited link the API redirects to, for your own downloader, a job runner or a CDN pull.

downloadBytes()

The build in memory, for a small database or a pipeline that never touches a filesystem.

metadata()

Row count, file sizes and when the build last updated. Poll it and fetch only when a new one has landed.

checksums()

The md5, sha1, sha256 and sha512 digests of one file, to verify it once it lands.

import os
from internetdata import InternetData
 
client = InternetData(os.environ["INTERNETDATA_API_KEY"])
 
# what is in today's build, without moving the file
meta = client.database.metadata("ip_rdns_v1")
 
client.database.download("ip_rdns_v1", "csvgz", "./ip_rdns_v1.csv.gz")
sums = client.database.checksums("ip_rdns_v1", "csvgz")
print(meta.updated, meta.entries, sums["sha256"])

load.pypip install internetdata

Also available for .NET, Ruby, Rust, Swift, Erlang, Perl and Zig. See all on GitHub →

Put it to work in your own systems.

Teams join IP RDNS against traffic they already log, inside their own infrastructure, and never send an address anywhere to get an answer.

Traffic context

A host name often says what an address is: a residential line, a mail server, a cloud instance.

Log enrichment

Name every address in a log without a PTR query per row.

License the full database

Sales will quote on volume, term and whether you need redistribution rights.

Checksums published per file: md5, sha1, sha256 and sha512.

The ID fixes the schema, so a new build never changes the columns your parser reads.

Samples are cut from the current build, not a synthetic extract.

Get a quote See documentation

Call the API in your language, with an official client.

All SDKs on GitHub →

Thirteen official clients, one for each language you ship in and one for the browser, plus middleware for fifteen web frameworks. Each answers private addresses without a request, caches what it looks up and splits big batches for you.

Node.js Web Python Go Java .NET PHP Ruby Rust Swift Erlang Perl Zig Express Fastify Next.js Django Flask FastAPI Laravel Symfony Rails Spring Boot ASP.NET Core net/http Gin axum Cowboy

Common questions

Read the docs →API reference →Email support →

On this page

What does a row tell us?

One address, the host name its PTR record returns, and whether that name's own forward record (A for IPv4, AAAA for IPv6) points back to the address: true, false, or empty when the name hasn't been checked yet. An address with no PTR record isn't in the file.

00 · Unlimited

Unlimited lookups, no sign-up.

Paste it into a terminal. Any address answers with its country, network, company and hostname, with no key and no daily or monthly cap. ASes and domains answer too.

curl https://api.internetdata.io/8.8.8.8

{
  "ip": "8.8.8.8",
  "is_tor": false,
  "is_anycast": true,
  "is_dns_resolver": true,
  "location": {
    "country": "US", ...
  },
  "asn": { "asn": 15169, ... },
  "hostname": "dns.google"
}

01 · Every field

All of the data on a paid plan.

VPN, proxy, hosting and CDN flags, each naming the operator.

Location to the city, with coordinates and an accuracy radius.

WHOIS records, the whole abuse contact and the services an address runs.

Up to 1,000 addresses, ASes and domains in one request.

A free API key answers every field for its first 100 lookups each day, with no card.

See pricing Get a free API key