Active DNS

Censys Active DNS is a high-frequency, iterative DNS resolution engine that maintains a proactive inventory of how domain names map to internet infrastructure. Instead of relying on passive observation, Censys actively performs DNS resolution, querying authoritative infrastructure to determine where domains currently resolve. This produces a continuously refreshed dataset describing domain-to-infrastructure relationships across the internet.

You can use Censys Active DNS to:

• View current and historical A, AAAA, CNAME, MX, NS, SOA, and TXT records for a domain. Records are resolved directly by Censys approximately every 24 hours.
• Analyze domain infrastructure changes and timelines. See exactly when a domain changed from one IP or another, how long it persisted, and what ran there.
• Instantly pivot from any domain to its host IP, open services, threats, certificates, and more. You can also pivot in the other direction from a host IP to see all domains that have ever been present on it.

Data from Censys Active DNS can be viewed and pivoted across in the Censys Platform UI and retrieved via the Platform API.

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Note

Censys Active DNS is a beta feature available to a select group of customers.

Domain information in the Platform UI

To directly look up a domain in Censys, enter its name in the Platform search bar, like censys.com.

To pivot to a domain details page directly from a host, web property, or certificate details page, you can click a domain name in the Reverse DNS or Forward DNS sections of the Summary. A limited selection of the DNS names associated with an asset are shown in these fields, check the DNS tab (described below) for additional names and record information.

DNS tab

On host pages, use the DNS tab to see all domains with A or AAAA records that point to the IP.

Domain record information and timeline

The following record information is available on the Records tab for a domain in the UI. Timestamps that indicate when each record was first seen and last seen by Censys' resolution service are shown for each entry.

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Note

Fully qualified domain names (FQDNs) are the absolute address of a specific asset or service within the DNS tree. On a FQDN details page, the resolution path and records displayed are strictly for the name currently being viewed, distinct from its parent domain or subdomains.

Subdomains that belong to another domain are indicated near the details page's title. Click the hyperlinked name to see the details page for the associated domain.

Record timeline

Click the Timeline tab to see a visual chart of historical record observations. Timestamps indicate when the record was first seen and last seen by Censys.

Record history availability

The amount of domain history your account has access to varies based on your license level.

Domain pivots

Use the pivot menu on domain pages to find hosts, web properties, and certificates associated with it.

Active DNS credit costs

The following table explains the credit costs for actions related to Active DNS functionality.

Retrieve domain information via API

Use the following endpoints to retrieve Censys Active DNS information via API.