3.2.1.3 Tables of Server Addresses
For each subnet, the client maintains a table of servers and their local addresses. Each row of the table represents a single server address and includes:
Its FQDN.
Its last known address in this subnet.
The UTC (Coordinated Universal Time) of the last time this address was refreshed.
The UTC time of the address is updated whenever a Hello or Probe-Match from the server is processed successfully and contains this address. A higher-layer protocol SHOULD also update the time when the server is successfully contacted through content retrieval (BITS Peer-Caching: Content Retrieval Protocol).