Which of the protocols below use TCP at the transport layer?（）

单项选择题You have just configured a static default route on router TK1. What is the purpose of a default route?（）

A. It is a route to be used when the routing protocol fails.
B. It is a route configured by an ISP that sends traffic into a corporate network.
C. It is a route used when a packet is destined for a remote network that is not listed in the routing table.
D. It is a route manually configured for a specific remote network for which a routing protocol is not configured.
E. It is used to send traffic to a stub network.

多项选择题Some of the TestKing routers have been configured with default routes. What are some of the advantages of using default routes?（）

A. They establish routes that will never go down.
B. The keep routing tables small.
C. They require a great deal of CPU power.
D. The allow connectivity to remote networks that are not in the routing table.
E. They direct traffic from the Internet into corporate networks.

单项选择题How does route poisoning work with holddown timers to prevent routing loops?（）

A. Information learned from one source is not distributed back to that source.
B. Routing updates from the poisoned source are ignored until a holddown timer expires.
C. Failed routes are advertised with infinite metrics.
D. New routing updates are ignored until the network has converged.
E. A route is marked as unavailable when its time-to-live is exceeded.

单项选择题What does a router do if it has no EIGRP feasible successor route to a destination network and the successor route to that destination network is inactive status?（）

A. It routes all traffic that is addresses to the destination network to the interface indicates in the routing table.
B. It sends a copy of its neighbor table to all adjacent routers.
C. It sends a multicast query packet to all adjacent neighbors requesting available routing paths to the destination network.
D. It broadcasts Hello packets to all routers in the network to re-establish neighbor adjacencies.

多项选择题Which of the following describe the process identifier that is used to run OSPF on a router?（）

A. It is logically significant.
B. It is globally significant.
C. It is needed to identify a unique instance of an OSPF database.
D. It is an optional parameter required only if multiple OSPF processes are running on the router.
E. All routers in the same OSPF area must have the same process ID if they are to exchange routing information.