Related to Host.io vs IP to Hosted Domains
These two features answer different questions, but it’s worth knowing how they can overlap.
hosted_domains (offered as a custom API or DB download from IPinfo) answers: “What else lives on this same server?” It’s based purely on network colocation which is domains that resolve to the same IP address. Useful for shared-hosting/CDN discovery, IP reputation, and attack-surface mapping off an IP.
related_domains (available on Host.io) answers: “What else is connected to this domain by ownership or configuration?” It looks at signals like shared nameservers, mail servers, site redirects, and other ownership indicators. Useful for portfolio discovery, brand protection, and competitive/fraud intelligence.
Where they diverge: for most domains, these two views barely overlap. A domain sharing a CDN IP with thousands of unrelated sites won’t show up as “related” by ownership, and a company’s domains scattered across many different IPs won’t show up as “hosted” together.
Where they converge: for a domain that manages a large owned portfolio where parking variant spellings, campaign domains, or regional properties and redirecting them to a flagship site while also hosting them on the same infrastructure — the two datasets can overlap substantially, because the same underlying decision (one company, one hosting setup) produces both signals at once.
In that case, related_domains and hosted_domains aren’t strictly independent, but the overlap is a property of how that particular domain owner operates, not a general rule that one dataset is a subset of the other.
Practical takeaway: treat them as complementary lenses rather than duplicates. Query both when you need full attack-surface or brand-protection coverage but neither one alone reliably substitutes for the other, but expect the overlap to grow the more a domain owner consolidates its properties onto shared infrastructure.