Passive DNS Lookup — Observed Host-to-IP Resolutions
Host-to-IPv4 correlation from passive observations — not live authoritative DNS
How to Use This Tool
- Enter apex domain or hostname to search passive index.
- Domain is normalized and validated.
- hostsearch API returns comma-separated host,ip lines.
- Lines parse into records with validated IPv4 addresses.
- count totals matches; display caps at 200 pairs.
- Compare against live DNS from historical DNS lookup to spot drift.
About This Tool
Passive DNS databases record what resolvers worldwide historically saw when names resolved — independent of what authoritative DNS publishes right now. VSPIC passive DNS lookup queries hackertarget hostsearch for the domain you enter and returns records array of host and ip pairs (up to 200 rows), count, source label, and note that passive DNS reflects observations, not authoritative truth.
Analysts use passive DNS to find shadow hosts, legacy A records still indexed after cutover, and sibling hostnames on shared infrastructure during threat hunts. Empty results mean the feed lacks observations — run historical DNS lookup for live authoritative snapshot comparison.
Common use cases
- •View all DNS records of a domain after migration
- •Confirm DNS records after domain changes
- •Test for DNS leaks when using a VPN
- •Debug email delivery with MX and TXT records
Why use VSPIC for ?
- Host and IP pairs in structured JSON for graph tools.
- Surfaces historical resolutions authoritative DNS no longer publishes.
- Free entry point before commercial passive DNS subscriptions.
- Explicit note distinguishes passive vs authoritative semantics.
- Useful for threat intel pivots on suspicious apex domains.
- Pairs with subdomain discovery for broader hostname coverage.
Passive versus authoritative DNS
Authoritative DNS is what the zone owner publishes now. Passive DNS is what the internet observed over time. Attackers may drop malicious A records quickly while passive indexes retain pivot clues for incident responders.
Our note field states passive DNS reflects observations — always confirm malicious IPs are still relevant with live lookup and reputation checks before blocking.
Reading host and ip records
Each record pairs hostname with IPv4 observed in the feed. Multiple IPs for one host suggest load balancing or migration windows. Multiple hosts pointing at one IP suggest shared hosting — pivot to neighbor domains lookup.
Hostnames may include www, api, or staging labels not obvious from apex-only live queries.
Threat hunting workflows
Start from phishing apex passive DNS to find historical bulletproof IPs. Cross-reference IPs on malware IP checker and spamhaus lookup. Pivot to reverse IP mode in historical hosting lookup for co-tenants.
Export records into your SIEM graph linking domains, IPs, and timestamps from other feeds.
Empty results are common
Low-traffic domains, recent registrations, and privacy-conscious hosts may never appear in free hostsearch. Absence does not prove cleanliness — continue with subdomain discovery and live DNS snapshot.
Retry after delay if API count exceeded messages appear in empty responses.
Comparison with historical DNS lookup
Historical DNS lookup captures authoritative live snapshot with queriedAt. Passive DNS lookup shows observed pairs that may include retired addresses. Run both — divergence highlights migration or hijack timelines.
Together they answer what is live and what the internet remembers.
API passive-dns action
GET /ip-tools/api/extended?action=passive-dns&domain=example.com. Parse records, count, source, note. Integrate with case tickets — cite source field as hackertarget hostsearch.
Do not treat passive data as sole evidence for takedown — corroborate.
Authorization
Research domains involved in authorized security investigations or assets you administer. Passive data is derived from public internet observation.
Important notes & limitations
- Feed coverage gaps — many domains return zero records.
- IPv6 observations not emphasized in hostsearch pairs.
- Rate limits and API quotas can empty results temporarily.
- Observations may be stale — verify live DNS before enforcement.
- Not a full SecurityTrails-style multi-year archive.
Frequently Asked Questions
Yes. VSPIC offers this passive DNS lookup at no cost with no account required. Results load in real time.
We do not permanently store your queries on our servers. Some tools run entirely in your browser; others fetch public data for the request only.
Yes. Open the page in any modern phone or tablet browser. Results work on Wi‑Fi and mobile data.
No. Passive shows historical observations. Live authoritative answers come from historical DNS lookup or dns-lookup tools.
The hostsearch feed format emphasizes IPv4 pairs. IPv6 passive coverage is limited in this free path.
Timestamps are not always provided per row. Treat as untrusted stale intel until verified live.
Some subdomain hostnames appear if indexed. Use subdomain discovery for certificate transparency coverage.
hackertarget hostsearch — cited in the source field of API JSON.
It is a free pivot aid. Large SOCs often add commercial passive DNS for depth and timestamps.
Next step for your check
Continue with historical dns lookup on VSPIC.
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