Reverse IP Lookup

Find all hostnames and domains currently resolving to a specific IP address using passive DNS databases.

About Reverse IP (Virtual Hosting)

A Reverse IP Lookup is different from a Reverse DNS (PTR) lookup. A PTR record only points to a single canonical hostname designated by the IP owner.

In contrast, Reverse IP uses passive DNS databases to find everyone who has pointed an A/AAAA record at that IP. In the modern era of cloud computing and shared hosting (like GoDaddy, cPanel, or Cloudflare), a single IP address can host thousands of entirely unrelated websites.

Security Context: This tool is frequently used in threat intelligence to discover if a suspicious domain is sharing a server with other malicious sites, or to map out an organization's hidden attack surface.

Our Reverse IP Lookup finds other domains hosted on the same IP address. Use it to see who shares your server, to map an organisation infrastructure during assessment, or to understand the neighbourhood your site sits in.

What is a Reverse IP Lookup?

A reverse IP lookup finds the domains that resolve to a given IP address. It is distinct from reverse DNS, which returns the single PTR hostname registered for an address.

Most web servers host many sites on one address using virtual hosting, where the server reads the Host header or the TLS SNI field to decide which site to serve. Shared hosting providers routinely place hundreds or thousands of sites on a single IP.

The data does not come from DNS itself, because DNS provides no way to ask which names point at an address. Providers build it by crawling large volumes of DNS records and passive DNS data, which means results are a snapshot of what was observed rather than a definitive list.

Finds domains resolving to a shared IP address
Different from reverse DNS, which returns one PTR hostname
Virtual hosting lets one address serve many sites
Built from crawled and passive DNS data, not queried directly
Results are indicative rather than complete

Why Reverse IP Lookups Matter

On shared hosting, your neighbours affect you. If a site sharing your address is blacklisted for spam or malware, the address reputation suffers and your mail deliverability and search visibility can suffer with it. Knowing who you share with is the first step in deciding whether a dedicated address is worth the cost.

In security assessment, reverse IP is a reconnaissance technique. An organisation hosting several properties on one address reveals the relationships between them, and a forgotten staging or legacy site sharing an address with production is a common way into an environment that is otherwise well defended.

A blacklisted neighbour damages shared address reputation
Reveals relationships between an organisation properties
Forgotten staging sites on production addresses are a common weak point
Helps decide whether a dedicated IP is justified
Shows whether a site sits behind a CDN or on origin infrastructure

How This Reverse IP Lookup Works

The tool queries hostname datasets associated with the address.

Validates the IP address input against format and SSRF safety checks
Queries datasets mapping hostnames to the address
Collects the domains observed resolving to it
Returns the list with the total count found
Notes where results are likely to be partial

How to Use the Reverse IP Lookup

Enter an IPv4 address in the input field
Run the lookup to retrieve associated domains
Review which other sites share the address
A very large count usually indicates shared hosting or a CDN
Treat the result as indicative, since no dataset is complete

Understanding Your Reverse IP Results

The result is a list of domains and a count, each carrying different implications:

Field / Value	Meaning
`One or few domains`	A dedicated or lightly shared address. Your reputation is largely your own, which is preferable for anything sending email.
`Dozens to hundreds`	Shared hosting. Reputation is pooled across every site on the address, so a single bad neighbour affects everyone.
`Thousands`	Almost certainly a CDN or large reverse proxy. The address does not represent a single origin server, so the list says little about any particular site.
`Related domains`	Several domains clearly belonging to one organisation. In assessment this maps the relationships between properties that are not otherwise obviously connected.
`Staging hostnames`	Names such as dev, staging or test sharing a production address. These are frequently less hardened and are a recurring finding in security reviews.
`Incomplete results`	Datasets are built from crawled and passive DNS, so domains never observed will be missing. An empty result does not prove the address is unshared.

Common Problems & How to Fix Them

You are on shared hosting, where IP reputation is pooled. A spamming or malware-hosting neighbour can get the address blacklisted, affecting your email deliverability and potentially your search visibility.

If you send email from this address, move to a dedicated IP. For web traffic the impact is smaller, but a shared address that appears on blacklists is still worth escaping.

Non-production sites are typically less hardened, run older code, and often expose debug interfaces or test credentials. Sharing an address with production means an attacker who compromises one has a foothold adjacent to the other.

Move non-production environments to separate infrastructure, restrict them by source address, and put them behind authentication.

The datasets are built from observed DNS data and are never complete. An address behind a CDN may also not be directly associated with any domain.

Treat an empty result as inconclusive rather than as proof the address is unshared. Cross-reference with certificate transparency logs, which often reveal hostnames that reverse IP data misses.

When a site sits behind a CDN, the address you see belongs to the CDN and is shared with a vast number of unrelated sites.

This is working as intended — the origin address is hidden, which is one of the security benefits of a CDN. Ensure the origin does not also respond directly on a publicly known address, which would defeat the protection.

Best Practices

Use a dedicated IP address for anything that sends email
Check who shares your address before committing to a hosting provider
Keep staging and development environments on separate infrastructure
Monitor the reputation of the address your mail originates from
Treat reverse IP results as indicative rather than complete
Cross-reference with certificate transparency for a fuller hostname picture
Ensure a CDN-protected origin does not also answer on a discoverable address

Security Recommendations

Audit your own addresses to find forgotten sites sharing infrastructure with production
Remember an attacker uses reverse IP to map your estate, so assume the relationships are visible
Isolate non-production environments, since they are frequently the weakest point in an otherwise well-defended estate
Be aware that shared hosting means a neighbour compromise can affect you through shared reputation and sometimes shared resources
Verify that your origin server is not directly reachable when you rely on a CDN for protection
Combine reverse IP with certificate transparency and subdomain discovery for a complete attack surface picture

Frequently Asked Questions

A lookup that finds which domains resolve to a given IP address. It differs from reverse DNS, which returns the single PTR hostname registered for an address rather than every domain pointing at it.

Reverse DNS queries a PTR record and returns one hostname, the name the address owner registered. Reverse IP lookup searches crawled DNS datasets for every domain observed resolving to that address, which may be thousands.

Virtual hosting. A web server reads the Host header or TLS SNI field to decide which site to serve, so one address can host many sites. Shared hosting providers routinely place hundreds or thousands on a single address.

It can. IP reputation is pooled, so a neighbour sending spam or hosting malware can get the address blacklisted, which affects your email deliverability. For web traffic alone the impact is generally minor.

The datasets are built from observed DNS data and are never complete. An address may genuinely host one site, sit behind a CDN, or simply not appear in the dataset. An empty result is inconclusive.

For sending email, yes — reputation matters and you do not want it shared. For web hosting alone the case is weaker, since search engines have long stated that shared hosting is not itself a ranking problem.

Yes, and they do. It maps the relationships between an organisation properties and frequently reveals forgotten staging or legacy sites sharing infrastructure with production. Auditing your own addresses first is the sensible response.