When troubleshooting the issue， you notice the election of a new root bridge with an unknown MAC address. Knowing that all access ports have the PortFast feature enabled， what would be the easiest way to resolve the issue without losing redundant links？（）

Youarethenetworkadministratorofamedium-sizedcompany，and...

多项选择题You are the network administrator of a medium-sized company， and users are complaining that they cannot send emails to some organizations. During your troubleshooting， you notice that your DNS MX record is blacklisted by several public blacklist filters. After clearing these listings for your IP address， and assuming that your email server has the right virus protection in place， what are two possible solutions to prevent this from happening in the future？（）

AfterapplyinganewACLonadevice，itsCPUutilizationrosesign...

单项选择题After applying a new ACL on a device， its CPU utilization rose significantly and many messages starting with "%SEC-6-IPACCESSLOG" appeared on the Syslog server. What can be done to resolve this situation？（）

Whichfeaturewouldpreventguestusersfromgainingnetworkacc...

单项选择题Which feature would prevent guest users from gaining network access by unplugging an IP phone and connecting a laptop computer？（）