What is the most common cause of network congestion？（） aggregation congestion occurring at the core layer where the different distribution layer devices feed traffic to the core-layer switches。 speed mismatches when moving from a low-speed LAN environment to a higher speed WAN environment。 flapping Ethernet interfaces caused by misconfigured LAN interfaces。 flapping serial interfaces caused by misconfigured WAN interfaces。 speed mismatches when moving from a high-speed LAN environment to a lower speed WAN environment。
齿轮油泵是一种能量转换装置，它是液压系统的（）装置。 动力；。 控制；。 执行；。 辅助。。
Which three of these statements about PPPoE are true？（） PPPoE can provide a host with access to a destination over Ethernet. You can have only one PPPoE session per PVC。 You must install PPPoE client software on all hosts that connect to the Ethernet segment. This means that the access provider must maintain a CPE。 You cannot use PPPoE with Cisco Service Selection Gateway。 PPPoE implementation is susceptible to broadcast storms and possible denial-of-service attacks。 Per-session accounting is possible， which allows the service provider to charge the subscriber based on session time for various services offered. The service provider can also require a minimum access charge。
What level of logging is enabled on a Router where the following logs are seen？（） alerts。 critical。 errors。 notificatio。
在冯特提出的情绪三维理论中，下面哪一个维度不包含在其中（） 愉快—不愉快。 激动一平静。 注意一拒绝。 紧张一松弛。
刚性好变形小的电器绝缘件，应使用（）
