Ack-Requested: This element lets the client determine whether an acknowledgement should be returned for a message sent.

Ack - Requested：这一元素允许客户端来决定对于发送的消息是否需要确认。

youdao

If the client successfully receives this acknowledgement, the client completes the handshake with an ack acknowledgement.

如果客户机成功地收到这个确认，就通过发送ack确认完成握手。

youdao

If a block is received successfully, a positive (ack) acknowledgement is returned.

如果成功接收了一个街区，一个正返回确认(ack)。

youdao