Reachable node
A public endpoint that completed the expected Bitcoin P2P handshake on its latest stored successful check. A reachable label is time-sensitive and does not prove full synchronization, trustworthiness or continuous availability.
Observed address
An address and port learned during a crawl. Observation alone does not establish reachability. The homepage's distinct crawl observations and the country page's node records use different source tables; do not assume their totals always match.
Advertised unreachable node
An address learned through peer advertisements but not confirmed reachable from the crawler. The label does not count as a reachable node and does not imply that the endpoint never runs Bitcoin software.
Unreachable and stale
Unreachable records did not complete the expected check. The UI unreachable filter also includes advertised unreachable records. The stale filter selects records with no check or a check older than 24 hours; it can overlap a stored reachable status. Staleness is about age, not a new successful probe.
User agent and protocol version
The user agent is a self-reported software string. Protocol version describes the peer's reported P2P protocol capability. Neither independently verifies the installed binary or the operator's policy preferences.
Services and block height
Services is a protocol capability bit field reported during the handshake. The starting block height is the peer's reported height at connection time; it can be missing, outdated or inaccurate. These values are not an independent audit of the peer.
ASN, country and coordinates
An autonomous system number identifies a routing network. A network name may describe a provider, not the node operator. Country and coordinates come from optional approximate IP geolocation; unknown values remain unknown and Tor addresses are not physically mapped.
IPv4, IPv6 and Tor
These identify address/network families, not separate Bitcoin blockchains. Observed IPv6 addresses may appear before a crawler can reach any of them. Tor/onion checks require an explicitly enabled proxy path; public reachability depends on the crawler's connectivity.
Continue with Bitcoin node statistics, inspect observed node records, or use the public data API. The data glossary defines the labels used throughout Atlas.