This object enables or disables use of access control lists when sorting candidate IP addresses for this hostname, removing any server from consideration whose ACL doesn't permit the requesting client's IP. This lets an admin enforce per-server access restrictions as part of server selection itself, since a server that would otherwise score well on latency or load metrics gets excluded entirely if the client isn't permitted, rather than being selected and then rejected at the application layer. An admin restricting a particular backend server to only internal corporate client IPs would enable this and configure a matching ACL, so external clients are automatically routed to a different, publicly-accessible server instead.