证券公司不得利用客户的交易编码、资金账号或者期货结算账户进行期货交易。（)A．正确B．错误

Intermediate system to intermediate system (IS - IS), is a protocol used by network devices (routers) to determine the best way to forward datagrams through a packet - switched network, a process called routing. Which three attributes are of the IS - IS routing protocol？ （）

A. supports VLSM

B. link - state routing protocol

C. operati on is similar to BGP

D. supports two routing levels within an autonomous system

●Border Gateway Protocol(BGP) is inter-autonomous system (71) protocol. BGP is based on a routing method called path vector routing. Distance vector routing is not a good candidate for inter-autonomous system routing because there are occasions on which the route with the smallest (72) count is not the preferred route. For example, we may not want a packet through an not secure even though it is the shortest route. Also, distance vector routing is unstable due to the fact that the routers announce only the number of hop counts to the destination without actually defining the path that leads to that (73) ．A router that recevives a distance vector advertisement packet may be fooled if the shortest path is actually calculated through the receiving router itself. Link (74) routing is also not a good candidate for inter-autonomous system routing because an Internet is usually too big for this routing method. To use link state routing for the whole internet would require each routex to have a huge link state database. It would also take a long time for each router to calculate its rousting (75) using the Dijkstra algorism.

（71）

A. routing

B. switching

C. transmitting

D. receiving

(72)

A. path

B. hop `

C. route

D. packet

(73）

A. connection

B. window

C. source

D. destination

(74)

A. status

B. search

C. state

D. research

(75）

A. table

B. state

C. metric

D. cost

●Border Gateway Protocol(BGP) is inter-autonomous system (71) protocol. BGP is based on a routing method called path vector routing. Distance vector routing is not a good candidate for inter-autonomous system routing because there are occasions on which the route with the smallest (72) count is not the preferred route. For example, we may not want a packet through an not secure even though it is the shortest route. Also, distance vector routing is unstable due to the fact that the routers announce only the number of hop counts to the destination without actually defining the path that leads to that (73) ．A router that recevives a distance vector advertisement packet may be fooled if the shortest path is actually calculated through the receiving router itself. Link (74) routing is also not a good candidate for inter-autonomous system routing because an Internet is usually too big for this routing method. To use link state routing for the whole internet would require each routex to have a huge link state database. It would also take a long time for each router to calculate its rousting (75) using the Dijkstra algorism.

（71）

A. routing

B. switching

C. transmitting

D. receiving

(72)

A. path

B. hop `

C. route

D. packet

(73）

A. connection

B. window

C. source

D. destination

(74)

A. status

B. search

C. state

D. research

(75）

A. table

B. state

C. metric

D. cost

Border Gateway Protocol(BGP) is inter-autonomous system (71) protocol. BGP is based on a routing method called path vector routing. Distance vector routing is not a good candidate for inter-autonomous system routing because there are occasions on which the route with the smallest (72) count is not the preferred route. For example, we may not want a packet through an not secure even though it is the shortest route. Also, distance vector routing is unstable due to the fact that the routers announce only the number of hop counts to the destination without actually defining the path that leads to that (73) ．A router that receives a distance vector advertisement packet may be fooled if the shortest path is actually calculated through the receiving router itself. Link (74) routing is also not a good candidate for inter-autonomous system routing because an Internet is usually too big for this routing method. To use link state routing for the whole internet would require each router to have a huge link state database. It would also take a long time for each router to calculate its rousting (75) using the Dijkstra algorism.

（71）

A. routing

B. switching

C. transmitting

D. receiving

（72）

A. path

B. hop

C. route

D. packet

（73）

A. connection

B. window

C. source

D. destination

（74）

A. status

B. search

C. state

D. research

（75）

A. table

B. state

C. metric

D. cost

A. A routed protocol is assigned to an interface and determines the method of packet deliver.

B. A routing protocol determines the path of a packet through a network.

C. A routed protocol determines the path of a packet through a network.

D. A routing protocol operates at the transport layer of the OSI model.

E. A routed protocol updates the routing table of a router.

A. A routing protocol is assigned to an interface and determines the method of packet delivery.

B. A routed protocol is assigned to an interface and determines the method of packet delivery.

C. A routing protocol determines the path of a packet through a network.

D. A routed protocol determines the path of a packet through a network.

E. A routing protocol operates at the transport layer of the OSI model.

F. A routed protocol updates the routing table of a router.

A.The PFE floods the packet out of all interfaces.

B.The PFE drops the packet and sends a destination unreachable notification back to source device.

C.The PFE forwards the packet to the routing engine for furtherprocessing.

D.The PFE queues the packet and sends are quest for a layer3 lookup to the routing engine.

A．more bit

B． partition bit

C． attached bit

D． overload bit

A.Global Packet Radio Service

B.General Packet Radio Service

C.General Packet Radio System

D.Global Packet Radio System

ks at the destination address of the packet, and forwards the packet to one of its network interfaces. The forwarding decision is usually done by looking up the destination address from another data structure called a forwarding table. The forwarding table is created by the router using the routing table and possible routing policies existing in the router. The router then creates a table where it lists which networks are accessible through which of the router’s network interfaces. An IP router looks at every IP packet individually and does the forwarding decision on a packet-by-packet basis. If something changes in the router’s routing table, a packet can take a different route from a preceding packet even if it has the same destination.] From the paragraph above，we can see that the router （） a forwarding table according to the routing table and possible routing policies existing in the router. When an IP packet arrives at a router, the （） part of packet is normally checked by the router. An IP router checks every IP Packet individually and makes the forwarding decision based on （）.

A．is generating B．generate C．is generated D．generates A．forwarding table B．network interfaces C．routing policies D．destination address A．the destination address and network interfaces B．forwarding table and network interfaces C．the destination address and forward table D．routing policies and routing table