Why is STP required when VLANs span access layer switches?（）

单项选择题When is a first-hop redundancy protocol needed in the distribution layer?（）

A. when HSRP is not supported by the design
B. when multiple vendor devices need to be supported
C. when preempt tuning of the default gateway is needed
D. when a robust method of backing up the default gateway is needed
E. when the design implements Layer 2 between the access switch and the distribution switch
F. when the design implements Layer 3 between the access switch and the distribution switch

单项选择题Which of these recommended designs provides the highest availability?（）

A. map the Layer 2 VLAN number to the Layer 3 subnet
B. control route propagation to edge switches using distribute lists
C. use a Layer 2 distribution interconnection link with HSRP or GLBP
D. use a Layer 3 distribution interconnection link with HSRP or GLBP
E. use equal-cost Layer 3 load balancing on all links to limit the scope of queries in EIGRP

单项选择题Which of these is a correct description of SSO?（）

A. It will only become active after a software failure.
B. It will only become active after a hardware failure.
C. It requires that Cisco NSF be enabled in order to work successfully.
D. It synchronizes the MAC, FIB, and adjacency tables between Active and Standby Route Processors.

单项选择题Which of these statements is correct regarding SSO and Cisco NSF?（）

A. Utilizing Cisco NSF in Layer 2 environments can reduce outages to one to three seconds.
B. Utilizing SSO in Layer 3 environments can reduce outages to one to three seconds.
C. Distribution switches are single points of failure causing outages for the end devices.
D. Utilizing Cisco NSF and SSO in a Layer 2 environment can reduce outages to less than one second.
E. NSF and SSO with redundant supervisors have the most impact on outages at the access layer.

单项选择题To which switch or switches should you provide redundant links in order to achieve high availability with reliable fast convergence in the enterprise campus?（）

A. to a core switch running Cisco NSF and SSO from redundant distribution switches connected with a Layer 2 link
B. to a core switch running Cisco NSF and SSO from redundant distribution switches connected with a Layer 3 link
C. to two core switches from redundant distribution switches connected with a Layer 2 link
D. to two core switches from redundant distribution switches connected with a Layer 3 link
E. to two core switches running Cisco NSF and SSO from two redundant distribution switches running Cisco NSF and SSO