Why one address can have many domains
Shared web hosting, reverse proxies, content delivery networks, SaaS platforms, parking systems, and large managed networks can place many unrelated hostnames on one public address. Address reuse and historical retention increase the observed set further.
Co-location is not affiliation
An IP association can establish that names shared an infrastructure observation. It does not establish the same owner, operator, customer, content, intent, or risk. The denser and more obviously multi-tenant the address, the weaker a bare co-location claim becomes.
Handle large results progressively
Dense sets should be retrieved and written incrementally so the client remains responsive and partial progress is useful. Choose a dedicated output location, avoid duplicate jobs, retain the input and scan time, and verify that the output continues to grow during long work.
Reduce the set according to the question
Normalize case, remove exact duplicates, group by registrable domain when appropriate, flag infrastructure-owned hostnames, and prioritize names matching the investigation’s lawful scope. Do not discard the raw export; work from a copy so filtering decisions remain auditable.
Compare density over time carefully
Use the same provider, product version, input, and plan allowance when comparing snapshots. A lower count can reflect migration, data processing, or a plan ceiling—not necessarily a real reduction in tenants. Record those constraints with the comparison.
Report the infrastructure context
State that the address appears shared, identify the evidence for that classification, describe the observation date, and avoid entity-level conclusions without independent corroboration. If a specific domain currently resolves elsewhere, say so directly.