WTRUs, ARSs, APs, WLG/AAA proxies, networks, and methods thereon are disclosed for fast security setup on a multi-RAT WTRU. Methods of sharing security associations between RATs on a multi-RAT WTRU are disclosed. Methods of caching security associations are disclosed. Methods are disclosed for alerting an ANDSF server of an AP that should be considered for association. Enhancements to advertisements from an AP are disclosed where the advertisements may include SSID with a FQDN, a HESSID type information, or TAI type information. Methods of resolving AP identities to a reachable address are disclosed. An address resolution protocol is disclosed for resolving AP identities. ARSs are disclosed that may resolve a BSSID to a network routable address. Protocols for carrying AP identities and security parameters are disclosed. Methods are disclosed of using ANDSF to provide the WTRU with security information and parameters of an AP. An RSN may indicate security capabilities.