Which three modes are the operating of HDLC？（）

A.SLA sender target can be an IP host
B.SLA sender sends a probe packet and a response probe packet
C.SLA sender sends a probe packet
D.SLA sender target must be a router
E.SLA sender target can be an IP SLA responder

A.You must install PPPoP client software on all hosts that connects to the Ethernet segment this means that the access provider must maintain a CPE
B.PPPoP can provide a host with access to a destination over Ethernet. You can have only one PPPoPsession per PVC
C.PPPoP implementation is susceptible to broadcast storms and possible denial-of-service attacks
D.You cannot use PPPoP with Cisco Service Selection Gateway
E.Per-session accounting is possible， which allows the service provider to charge the subscribe based onsession time for various services offered. The service provider can also require a minimum access change

A.The path cost can be changed for an interface using the spanning-tree cost command
B.The path cost can be changed for an interface using the stp path-cost command
C.The SPT default path cost depends on the interface speed
D.The STP default path cost is similar for all interface