在rip中metric等于（）为不可达。

A.NAT protects network security because privat enetworks are not advertised.
B.NAT accelerates the routing process because no modifications are made on the packets.
C.Dynamic NAT facilitates connections from the outside of the network.
D.NAT facilitates end-to-end communication when IPsec is enable.
E.NAT eliminates the need to re-address all host that require extemal access.
F.NAT conserves addresses through host MAC-level multiplexing.

A.直接路由、静态路由、rip、ospf
B.直接路由、ospf、静态路由、rip
C.直接路由、ospf、rip、静态路由
D.直接路由、rip、静态路由、ospf

A.默认路由。
B.直接路由。
C.间接路由。
D.以上都不对。