This read-only object records whether a given authentication history entry was an attempt against the primary(0) or secondary(1) AAA server, noting the NID falls back to the secondary if the primary rejects or is unavailable. A technician uses it to see the actual failover pattern the NID exhibited during a series of authentication attempts. For example, seeing several consecutive entries flip from primary to secondary would confirm the NID correctly failed over when its primary AAA server became unavailable.