单选题What is true regarding Autonomous Systems （AS ）？（）A AS numbers are assigned by the IANAB AS numbers are used by BGP （Border Gateway protocol ） to exchange IP routing information with neighboring ASC In the internet， an Autonomous System （AS） is a colle

The Border Gateway Protocol(BGP)is an interautonomous system【S1】protoco1．The primary function of a BGP speaking system is to exchange network【S2】information withother BGP system．This network reachability information includes information on the list of Auton0．mous System(ASs)that reachability information traverses．BGP一4 provides a new set of mecha-nisms for supposing【S3】interdomain routing．These mechanisms include support for adver-tising an IP【S4】and eliminate the concept of network class within BGP．BGP-4 also intro-duces mechanisms that allow aggregation of routes，including【S5】of AS paths．These chan-ges provide support for the proposed supernettting schem

【S1】

A．connecting

B．resolving

C．routing

D．supernettting

A.ARP

B.IGP

C.BGP

D.EGP

● The Border Gateway Protocol (BGP) is an interautonomous system （71） protocol. The primary function of a BGP speaking system is to exchange network （72） information with other BGP system. This network reachability information includes information on the list of Autonomous System (ASs) that reachability information traverses. BGP-4 provides a new set of mechanisms for supporting （73） interdomain routing. These mechanisms include support for advertising an IP （74） and eliminate the concept of network class within BGP. BGP-4 also introduces mechanisms that allow aggregation of routes, including （75） of AS paths. These changes provide support for the proposed supernettting scheme.

（71）

A. connecting

B. resolving

C. routing

D. supernettting

（72）

A. secubility

B. reachability

C. capability

D. reliability

（73）

A. answerless

B. connectionless

C. confirmless

D. classless

（74）

A. prefix

B. suffix

C. infix

D. reflex

（75）

A. reservation

B. relation

C. aggregation

D. connection

A. Within an AS, all routers must run either BGP or IBGP.

B. An AS uses exterior gatew ay protocols (EGPs) to exchange information with other autonomous systems.

C. An AS is a group of routers under the same technical administration.

D. Within an AS, routes learned through BGP can be redistributed using interior gateway protocols.

E. Wi thin an AS, routes learned through an interior protocol cannot be redistributed using BGP to other autonomous systems.

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

A. autonomous-system 64555;confederation 1111 ;

B. autonomous-system 64555; confederation 1111 members [ 64555 64777 ];

C. confederation 64555; autonomous-system 1111 members [ 64555 64777 ];

D. sub-autonomous-system 64555; confederation 1111 members [ 64555 64777 ];

A. The BGP split - horizon rule specifies that routes learned via EBGP are never propagated to other IBGP peers.

B. The BGP split horizon rule specifies that routes learned via IBGP are never propagated to other IBGP peers.

C. A full - mesh IBGP requires that neighbor relationships be established between a ll BGP enabled routers in the autonomous system.

D. IBGP neighbors must be in different autonomous systems.

E. An EGP or static routing is required between IBGP neighbors.

●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

A. It confines network instability to a single area of network.

B. It increases the routing overhead of the network

C. It supports VLSM

D. It routes between Autonomous Systems.

E. It allows extensive control of routing updates

F. None of the above

A. Advertise with a high MED value all networks that are discovered via external BGP.

B. Set the no - export community attribute on all networks that are advertised externally.

C. Remove the AS - Path information on all routes in the BGP table pr ior to advertising externally.

D. Set the origin code to incomplete for all networks that are discovered via external BGP.

E. Only advertise networks externally if they have been discovered via internal BGP.

F. Use an outgoing distribution list to filte r all networks not originating from inside the autonomous system.