Recognition Display IPv6 RA Guard Test: Block Rogue Router Advertisements
Intent: decide — A recognition display that suddenly loses its IPv6 default gateway, adopts an incorrect IPv6 prefix, or begins routing its content management system traffic through an unexpected path is not malfunctioning. It is responding exactly as IPv6 specifies: it received a Router Advertisement message and configured its network stack accordingly. The problem is that the Router Advertisement came from a rogue device on the same VLAN — a student laptop, a misconfigured access point, or a test device left plugged into a hallway data jack — rather than from the school’s actual IPv6 router. Without IPv6 RA Guard active on the serving switch, the display has no way to distinguish a legitimate advertisement from a rogue one, and the result is a display that appears to work fine on IPv4 while silently failing all IPv6-dependent content delivery, CMS connections, or DNS resolution. The failure is difficult to reproduce on demand, often misattributed to the display platform, and invisible to ping-based monitoring that tests only IPv4 reachability.
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