Rescanning a Host
Re-checking a single host's addresses and ports without sweeping its whole subnet.
A full discovery sweeps every configured subnet. When the question is narrower — is this one host still there, and is what we know about it current? — use Rescan from a host's menu in Assets > Hosts.
A rescan checks only that host's known addresses. Alongside the standard discovery port set it re-checks the ports already recorded on the host, so it both confirms what was there and surfaces services that have opened since.
Which daemon runs it
The daemon that last discovered the host — evidence it can reach the address, rather than a guess from subnet membership. If that daemon can no longer reach it, the rescan is refused rather than run at lower fidelity from somewhere else.
Where it shows up
In the Scans tab as an AdHoc run, with the same progress and cancel controls as any other scan. A Queued phase means the daemon is busy and will start when its current scan finishes.
How to read the result
Where the daemon's interface has a MAC address, it ARPs the target, which sees a live host even when every port is firewalled. On an interface without one — a point-to-point VPN tunnel, say — it falls back to a TCP probe, which cannot tell a firewalled host from an absent one.
When it is refused
Rescan is refused with the specific reason, when:
| Reason | What to do |
|---|---|
| The host has never been scanned, or the scan that found it is no longer on record | Run a discovery first |
| The daemon that last scanned it no longer exists | Run a discovery from another daemon to refresh the host |
| That daemon has moved to a different network | Scan the host from a daemon on its network |
| That daemon is older than 0.17.7 | Upgrade the daemon |
| That daemon has no interface on a subnet holding any of the host's scannable addresses | Deploy a daemon that does — see Planning Daemon Deployment |