This object records the last time this server was selected, or advertised, as the best server for a given subdomain or host name query. An admin uses this to spot a server that's configured and healthy-looking but hasn't actually been selected in a long time, which could indicate its metrics are consistently scoring worse than its peers or that it's effectively orphaned from real traffic. If this object for one server in a pool shows a timestamp from days ago while its peers show recent hits, an admin would investigate why that server keeps losing the selection comparison, perhaps a persistently high latency metric.