A second network card in a server that activates if the primary card fails is an example of which of the following network performance optimization？（）

A.Time required for a VPN connection to occur
B.Time required by protocols to update their forwarding tables after changes have occurred
C.Time required for an IDS to detect suspicious software
D.Time required by switch ports to update their link status and transition to the forwarding state

A.DHCP
B.DNS
C.WINS
D.NAT

A.UTP
B.T568A/B
C.STP
D.IEEE 802.5