This object records the public (internet-facing) IP address that the remote client was connecting from when this session attempt failed, essentially the client's external ISP address. An admin can use this to see whether failures are coming from a single external address or IP range - a strong signal of a targeted attack or a misconfigured remote site's NAT gateway - versus scattered addresses suggesting a broad, unrelated set of individual user problems. A run of failed attempts all sourced from the same public IP, say 203.0.113.45, hammering different usernames would be a clear brute-force indicator.