What methods can be used for fault location when PPPoE dial-up failure occurs in the Internet service? (Multiple Choice)

What methods can be used for fault location when PPPoE dial-up failure occurs in the Internet service? (Multiple Choice)
A . Check whether the device to user Modem is reachable
B . Check PITP configuration
C . Check whether the circuit alarm template is reasonable
D . Check whether an ACL that restricts PPPoE packets is configured

Answer: ABD