单选题When a local loopback is activated on a PPP serial link, what indicates that the local interface is good?（）A A ping to the local address succeeds.B A ping to the remote address succeeds.C A ping to the remote address received a 'TTL expired' message.D
题目
单选题
When a local loopback is activated on a PPP serial link, what indicates that the local interface is good?（）
A
A ping to the local address succeeds.
B
A ping to the remote address succeeds.
C
A ping to the remote address received a 'TTL expired' message.
D
The interface shows a flag indicating that a loop is detected.