This counts accounting responses from this server with invalid authenticator or signature attributes, the specific symptom of the accounting shared secret not matching between the switch and the server. Because the accounting secret is configured independently from the authentication secret, this counter climbing while the corresponding authentication server's bad-authenticators counter stays at zero is a clear sign the accounting-specific secret, not the login secret, is the one out of sync. For example, an admin who updates the RADIUS shared secret used for logins but not the separate one used for accounting would see this counter start climbing on every session's start and stop records while logins keep succeeding normally.