Before the client can send an AS or TGS message, it MUST discover the KDC to which the AS or TGS message will be sent. Clients SHOULD use SRV record discovery ([RFC4120] section 126.96.36.199) by default. When SRV record discovery is not supported by KDCs, clients can use a list of KDCs for a specified realm.
If the client has a ticket cache, the ticket cache MUST be initialized to an empty state.
All parameters that are specified in section 3.2.1 are reset and then set according to the higher-layer protocols request.