A. ipv6 host B. ipv6 unicast-routing C. ipv6 local D. ipv6 neighbor
单项选择题In the implementation of VLSM techniques on a network using a single Class C IP address,which subnet mask is the most efficient for point-to-point serial links?（）
A. 255.255.255.240 B. 255.255.255.254 C. 255.255.255.252 D. 255.255.255.0 E. 255.255.255.248
单项选择题Which IPv6 address is valid?（）
A. 2031:0:130F::9C0:876A:130B B. 2001:0DB8:0000:130F:0000:0000:08GC:140B C. 2001:0DB8:0:130H::87C:140B D. 2031::130F::9C0:876A:130B
单项选择题Which of the following protocols uses both TCP and UDP ports?（）
A. SMTP B. Telnet C. FTP D. DNS
单项选择题Which command enhances the 802.1D convergence time on ports that are connected to hosts?（）
A. spanning-tree backbonefast B. spanning-tree uplinkfast C. spanning-tree portfast D. spanning-tree cost512
单项选择题Which IEEE standard protocol is initiated as a result of successful DTP completion in a switch over FastEthernet?（）
A. 802.3ad B. 802.1w C. 802.1Q D. 802.1d
