Which statement about LACP is true?

The statement that the default mode of operation of an LACP interface is passive is accurate. In Link Aggregation Control Protocol (LACP), interfaces can operate in either active or passive mode. When an interface is configured to use LACP, it operates in passive mode by default unless configured otherwise. In passive mode, the LACP participant will only respond to LACP packets from its partner, whereas in active mode, it proactively sends LACP packets to initiate the aggregation process. This default setting is intentional to ensure that when devices are connected, they do not automatically form an LACP session without the acknowledgment of both parties, thereby preventing potential misconfigurations or unintended link aggregations in networks with mixed device capabilities.

In contrast, the other choices involve specific behaviors or characteristics of LACP that do not align with its default settings or operational requirements. The configuration of LACP, including enabling it on aggregated Ethernet interfaces or trunk groups, is not set to default and typically requires manual configuration. Additionally, the requirement for at least one side to be in passive mode is not a necessary condition for LACP operation, since one side can be in active mode, and the protocol will still negotiate the aggregation successfully.