Learn in the textbookAdvanced Threat Protection and Network Architecture / Communication Security
DefinitionA quarantine network (検疫ネットワーク) first connects a device that wants to join the internal LAN to a separate inspection segment, and lets it onto the internal LAN only after confirming it is safe.
ExplanationThe inspection checks the state of the device, such as whether operating system patches have been applied and whether antivirus software is up to date. Devices that fall short are kept off the internal LAN and held in the inspection segment until the fixes are done. The aim is to stop infections from spreading inside the company through devices that may have been connected to unknown networks elsewhere.
AnalogyIt follows the same flow as an airport quarantine station, where travelers returning from abroad are checked and let into the country only if nothing is wrong.
Memory hookThe Japanese name uses 検疫, meaning quarantine inspection: 検 is "to examine" and 疫 is "epidemic." As the characters say, a device is checked for infection before it is let in.