Host Domains API

The Host Domains API accepts an IP address and returns the domain names that share that host. To look up by domain name instead, use the Reverse IP API.

Understanding Host Domains Results

The Host Domains tool tracks a single IP address per domain. Because you query by IP directly, the response always represents a single IP address — ip_addresses is always an object, never an array.

• Results represent a subset of all domains on the IP, not an exhaustive list
• The domain_count value indicates the total number of domains known for that IP, which may exceed the number returned
• For shared hosting environments with many domains, you may see only a portion of the total

Use Cases and Limitations

Appropriate Use Cases

• Investigative research on specific IP addresses and their hosted domains
• Finding related infrastructure for a known IP
• Initial reconnaissance and hosting relationship mapping

Limitations for High-Volume IPs

The Host Domains API is not designed for:

• Exhaustive enumeration of large CDN or cloud hosting providers such as Cloudflare, Amazon Web Services, or Google Cloud
• Complete audits of high-volume IP addresses that host millions of domains
• Bulk data extraction at scale

For IP addresses hosting very large numbers of domains, the API returns only a subset. Full enumeration of all domains on high-volume IPs is not possible with this tool.

Alternative Tools

Iris Investigate API

The Iris dataset tracks all actively resolved IP addresses for apex domains and is updated daily. Iris is designed for investigative pivoting and finding related infrastructure but is not intended for mass enumeration.

Learn more about Iris Investigate

DNSDB

DNSDB provides broader historical DNS data coverage and can return more comprehensive reverse IP results.

Learn more about DNSDB

API Usage

https://api.domaintools.com/v1/64.246.165.240/host-domains/

ip_addresses is always a single object with ip_address, domain_count, and domain_names as direct children.

Host Domains Parameters

Optional Parameters	Value
limit	Limits the size of the domain list in the response.

If domain_count is greater than the number of elements in domain_names, the result has been limited. You’re seeing the first set of domains for that IP, listed alphabetically. Increasing the limit will not return a complete list for high-volume IPs because the underlying data tracks only one IP per domain.

Sample Response

{
  "response": {
    "ip_addresses": {
      "ip_address": "64.246.165.240",
      "domain_count": 4,
      "domain_names": [
        "domaintools.com",
        "domaintools.net",
        "domaintools.org",
        "whoislookup.com"
      ]
    }
  }
}

Sample Queries

• HTML: https://api.domaintools.com/v1/64.246.165.240/host-domains/?format=html
• JSON: https://api.domaintools.com/v1/64.246.165.240/host-domains/
• XML: https://api.domaintools.com/v1/64.246.165.240/host-domains/?format=xml