It is not always a malfunction that a device found yesterday uses a different IP today. Understanding the DHCP lease mechanism prevents confusion between device ID and address.
Basic approach
DHCP gives network configuration to clients for a certain period of time. The same address can be maintained during renewal; However, it is not guaranteed that the same address will always be given. Keeping MAC, device name, and last seen time in inventory alongside IP makes it easier to explain address changes.
Application steps
- Read DHCP status, server and lease times with ipconfig /all on Windows.
- Compare the router's lease list with the scan result in the same time period.
- Consider managed DHCP reservation for devices requiring constant access; Do not assign random addresses manually.
Practical example
If a printer shows .40 first and .63 after reconnecting, compare the MAC and model information before opening two separate printer records. The old DNS record may still show .40.
Interpret the result correctly
The lease list is not an online device list; The lease of closed clients may continue. Running ipconfig /release while connected remotely may disconnect you. For initial analysis, the read-only /all output is sufficient.
Source and follow-up reading
Protocol or command details: RFC 2131. The steps and example scenario are IPScans editorial narrative.