A. Spanning Tree Protocol （STP）
B. Delay reduction
C. Hot Standby Routing Protocol （HSRP）
D. Dynamic routing protocols
E. Quality of Service （QoS）
F. Jitter management

A. Router 172.16.11.112 will be the active router because its HSRP priority is preferred over router  172.16.11.111.
B. Router 172.16.11.111 will be the active router because its HSRP priority is preferred over router  172.16.11.112.
C. The IP address 172.16.11.111 is the virtual HSRP router IP address.
D. The IP address 172.16.11.112 is the virtual HSRP router IP address.
E. The nonpreempt feature is enabled on the 172.16.11.112 router.
F. The preempt feature is not enabled on the 172.16.11.111 router.