1. [单选题]当配置一个CISCO的路由器时，缺省的DR和BDR优先级是（）。
B. 1
C. 16
D. 255
2. [单选题]What is the purpose of the spanning-tree algorithm in a switched LAN?
A. To provide a monitoring mechanism for networks in switched environments.
B. To manage VLANs across multiple switches.
C. To prevent switching loops in networks with redundant switched paths.
D. To segment a network into multiple collision domains.
E. To prevent routing loops in networks.
