下面的問題將幫助你評價在本章中學(xué)習(xí)到的內(nèi)容。仔細(xì)閱讀所有的選項(xiàng)，因?yàn)檎_答案可能多于1個。選擇每個問題中所有的正確答案。
1) company a has recently merged with company b, which exists in the same building and is physically close enough for all the computers to belong on the same network seg ment.
company a uses an atm backbone and fast ethernet for all nodes. company b has a token ring environment on shielded twisted-pair wiring. why will company a and company b select a router for their newly merged network (公司a最近合并了公司b，它們位于同一座大樓中，并且所有的計算機(jī)足夠接近，可以屬于同一個跳。公司a在所有的節(jié)點(diǎn)上使用at m主干和快速e t h e r n e t公司b使用屏蔽雙絞線基礎(chǔ)上的令牌環(huán)網(wǎng)環(huán)境。為什么公司a和公司b為它們新的合并網(wǎng)絡(luò)選擇了路由)？
a. network segment size has reached the maximum
b. network addresses are not sufficient for a merged network
c. tr a ffic must be segmented to prevent an expected bandwidth overload
d. a router is the usual way to connect dissimilar network types
2) what are the two basic mechanisms that make up a routing protocol (構(gòu)成路由選擇協(xié)議的兩個基本機(jī)制是什么)？
a. route selection
b. flooding
c. autonomous systems
d. data tr a n s m i s s i o n
3) what is a routing table used for (路由選擇表的用途是什么)？
a. it is the physical support for the router to sit on
b. it contains a list of all the timers used to prevent routing loops
c. it is used to select the best route
d. it manages the periodic update algorithm
4) what types of information can be found in different types of routing protocol routing tables (在不同類型的路由選擇協(xié)議路由表中可以發(fā)現(xiàn)何種類型的信息)？(select 3)
a. the destination network associated with the next hop
b. the destination network associated with the cost metric
c. the destination network associated with the subnet mask
d. the destination network associated with the next path or interface to use
5) what is a routing update used for (路由選擇更新的用途是什么)？
a. routing updates notify neighboring routers with a 呼叫
b. routing updates redistribute routes learned from other routing protocols
c. routing updates maintain the routing table
d. routing updates increase the network addresses available by changing the subnet masks
6) when a node on one network sends a packet to a node on another segment that is three
hops away, what addresses are included in the initial addressing of that packet (select 2) (當(dāng)網(wǎng)絡(luò)上的節(jié)點(diǎn)向另一個跳3個跳上的節(jié)點(diǎn)發(fā)送信息表時，在那個信息表的初始地址中包含了什么地址)？
a. the network address of the router
b. the mac layer address of the router
c. the network address of the destination node
d. the mac layer address of the destination node
7) what are three objectives for a routing protocol (路由選擇協(xié)議的3個目標(biāo)是什么)？
a. accuracy
b. quick holddowns
c. rapid convergence
d. low overhead
8) define convergence (定義收斂)。
a. convergence is the updates that are triggered by network changes
b. convergence is the process of sending 呼叫packets
c. convergence is two routers merging their routing tables into one
d. convergence is the synchronizing of all routing tables on the internetwork, or simply the synchronization of a single route change across all routers.
9) why are dynamic routing protocols considered dynamic (為什么動態(tài)路由選擇協(xié)議考慮動態(tài))？
a. because each route is dynamically selected for each packet with a destination network not attached to the router。
b. because new routes are dynamically recomputed whenever there is a change in the nternetwork topology
c. because convergence happens faster
d. because all the routes remain the same no matter what changes happen on the network
10) what is a static route (什么是靜態(tài)路由)？
a. a static route is one that has been manually entered into the routing table and is not updated by a routing protocol
b. a static route is one that is recomputed whenever a change is made on the internetwork
c. a static route is one that is redistributed when it has been learned by another routing protocol
d. a static route is one that comes already configured in the router from the manufacturer
11) what type of network is best when using static routes (當(dāng)使用靜態(tài)路由時，何種類型的網(wǎng)絡(luò)是最好的)？
a. a large network with hundreds of routers and networks
b. a complex internetwork that changes often
c. an autonomous system with multiple connections to other autonomous systems
d. a small network with few routers and infrequent changes
12) what is an autonomous system (什么是自治系統(tǒng))？
a. an area
b. a domain
c. a contiguous set of routers defined within a larger internetwork, that do not share routing information with the external internetwork
d. all of the above
e. none of the above
13) what is a default route (什么是默認(rèn)路由)？
a. a type of static route
b. a destination for any nonroutable packet
c. gateway of last resort
d. all of the above
e. none of the above
14) what type of information does a distance vector router build its routing table with (距離向量路由器用何種類型的信息來建立它的路由選擇表)？
a. 呼叫packets
b. second-hand information
c. lsps
d. first-hand information
15) what is the count to infinity problem (什么是無限計數(shù)問題)？
a. a routing loop that results from the way distance vector protocols use second-hand information
b. the inability of routers to process more than 16 hops
c. the excessive cpu overhead presented by distance vector algorithms
d. the result of using both rip and igrp on the same internetwork
16) what is poison reverse (什么是破壞逆轉(zhuǎn))？
a. a change to the default update period timer
b. a routing loop that occurs when using second-hand information to update route tables
c. a router virus
d. a version of split-horizon that sends back a “route unreachable” update to the router that the route was learned from, in order to avoid routing loops
17) what is rip (什么是r i p )？
a. rip is an older distance vector interior gateway protocol with a 30-second update timer and . maximum of 15 hops (where “i n f i n i t y” is 16 hops)
b. rip is a new link-state protocol created by cisco
c. rip is a proprietary protocol created by cisco that has two versions; only version 2 is used currently
d. rip is a distance vector interior gateway protocol with a 224 maximum network diameter (maximum 224 hops)
18) what is igrp (什么是i g r p )？
a. igrp is an older distance vector interior gateway protocol with a 30-second update timer and a maximum of 15 hops (where infinity is 16 hops)
b. igrp is a new link-state protocol created by cisco
c. igrp is a proprietary protocol created by cisco that has two versions; only version 2 isused currently
d. igrp is a distance vector and interior gateway protocol with a 224 maximum network diameter (maximum 224 hops)
19) what is the purpose of a flash update in igrp (igrp中的瞬時更新的目的是什么)？
a. a flash update is a standard 90-second update
b. after three flash updates, a route is considered unreachable
c. a flash update is sent immediately upon a change in the network topology, in order to speed convergence
d. after seven flash updates, a route is removed from the routing table
20) how can the administrator change how igrp selects routes (管理員如何修改i g r p選擇路由的方法)？
a. the administrator can set update timers
b. the administrator can enable or disable split horizon
c. the administrator can set up load balancing across redundant routes
d. the administrator can adjust the metric weights used for determining the route selection
21) the way to get traffic from one segment of the network to another segment is (在網(wǎng)段之間進(jìn)行通信的方法是)：
a. bridging
b. routing
c. switching
d. all of the above
22) routing occurs at which layer (路由發(fā)生在哪一層)？
a. physical layer
b. data link layer
c. network layer
d. transport layer
23) in general, the bets route selected by a router is one with (一般而言，路由器選擇的最佳路由具有何種特性)？
a. least cost
b. shortest distance
c. lowest metric value
d. none of the above
24) a routing table typically includes which of the following (路由表通常包含下列的哪些信息)？
a. destination network address
b. the total number of networks
c. the number of nodes in each network
d. the total number of routers in a network
25) when a router receives a packet, it accepts or rejects a packet by examining what (當(dāng)路由器接受到數(shù)據(jù)包時，它通過檢查什么而決定接受或拒絕數(shù)據(jù)包)？
a. the mac address of the source of the packet
b. the address of the source network/node number
c. the address of the destination network/node
d. the mac address of the next router
26) low overhead of a routing algorithm is normally associated with (路由選擇算法的低代價通常和什么相關(guān))？
a. optimal route
b. cpu usage
c. accuracy
d. converg e n c e
27) convergence is not an issue if (收斂并不會成為一個問題，如果)：
a. routers are added to the network
b. some of the network interfaces are down
c. cpu/bandwidth usage of the routers changes
d. an invariant network topology is selected for the network architecture
28) an internet protocol (ip) router selects (網(wǎng)際協(xié)議( i p )路由器選擇)：
a. an entire path from source to destination
b. the next route step
c. the two adjacent routers to itself
d. all of the above.
29) ip route configuration command for a static route includes which of the following parameters (靜態(tài)路由的ip route配置命令包括下列哪一個參數(shù))？
a. subnetwork number of the destination network
b. subnet mask of the source network
c. ip address of the interface of the router which the packet should use
d. mac address of the next router on the path
30) given the following portion of the network:
network a→ router x→ router y→ network b
i n t e r f a c e : i n t e r f a c e : 8 6 . 0 . 0 . 0
x 0 y0
3 5 . 3 . 3 . 4
and assuming a network mask of 255.0.0.0 for both a and b networks, which one of the
following represents a correct command to configure router x to send data from network a to network b (給定網(wǎng)絡(luò)的下列端口：
網(wǎng)絡(luò)a→路由器x→路由器y→網(wǎng)絡(luò)b
接口： 接口： 8 6 . 0 . 0 . 0
x 0 y 0
3 5 . 3 . 3 . 4
并假設(shè)a和b網(wǎng)絡(luò)的網(wǎng)絡(luò)掩碼為2 5 5 . 0 . 0 . 0，則下面的哪一個代表了配置路由器x從網(wǎng)絡(luò)a向網(wǎng)絡(luò)b發(fā)送數(shù)據(jù)的正確命令)？
a. #ip route 85.0.0.0 255.0.0.0 35.3.3.3
b. #ip route 86.0.0.0 255.0.0.0 35.3.3.4
c. #ip route 86.0.0.0 255.0.0.0 35.3.3.3
d. #ip route 85.0.0.0 255.0.0.0 35.3.3.4
31) a static routing table can be changed at any time without manual intervention (靜態(tài)路由選擇表可以不經(jīng)人工干預(yù)而在任何時候修改)。
a. true
b. false
32) in a hybrid solution of static and dynamic routing, the nonroutable packets are sent to (在靜態(tài)和動態(tài)路由的混合解決方案中，不可路由的數(shù)據(jù)包發(fā)送到)：
a. the next router
b. the central router
c. the gateway of last resort
d. the source router where the packets originated
33) how is fault tolerance on a routing algorithm achieved (路由選擇算法如何實(shí)現(xiàn)容錯)？
a. by providing a central control router
b. by a distributed routing protocol
c. by load balancing of the traffic
d. all of the above
34) the configuration command ip defa u lt for a default static router requires which of the following parameters (默認(rèn)靜態(tài)路由器的配置命令ip defa u lt需要下列的哪一個參數(shù))？
a. network mask
b. router interface number
c. subnet id
d. network number
35) in a distance vector routing protocol, aging is set for (在距離向量路由選擇協(xié)議中，時 效為什么設(shè)置)？
a. only the next available router
b. all routing information
c. only the unavailable routers
d. only the routers in the lowest metric route
36) in a distance vector algorithm, the holddown interval for large or complex networks (在距離向量算法中，大型或復(fù)雜網(wǎng)絡(luò)的暫停間隔)：
a. cannot be used
b. would need to have a much larger value
c. is equal to negative reachability parameter
d. would need to have a smaller value to reach converg e n c e
37) what do link-state protocols use as a metric (鏈路狀態(tài)協(xié)議使用什么作為度)？
a. hops
b. cost
c. cpu usage
d. network operational time
38) flooding in link-state protocol means what (鏈路狀態(tài)協(xié)議中的泛洪法意味著什么)？
a. a router sending all routing information to its neighbors
b. a router broadcasting all information to all routers in the network
c. the neighbors of a link-state router receiving a link-state packet, copying it, and then
forwarding it to the rest of the network
d. a router sending information about the routers that have changed
39) which statement is true of interior gateway protocols (對內(nèi)部網(wǎng)關(guān)協(xié)議的陳述中，哪一 句是正確的)？
a. they apply to internet domains
b. they apply to autonomous systems within the network
c. they apply to external networks
d. they allow systems in the internet to manage areas in the network where igp is i m p l e m e n t e d
40) exterior gateway protocols are known as (外部網(wǎng)關(guān)協(xié)議又稱為)：
a. inter-domain
b. areas
c. domains
d. intra-domain
41) routing information protocol (rip) can have maximum of (路由信息協(xié)議( r i p )最多可以具有多少個跳計數(shù))？
a. 24 hops
b. 16 hops
c. 12 hops
d. 8 hops
42) how many commands are required to configure a router for rip (為路由器配置r i p需要多少個命令)？
a. four
b. three
c. two
d. one
43) rip authentication command can be used with which version of rip (rip鑒別可以和r i p的哪個版本一起使用)？
a. rip version 1
b. rip version 2
c. rip version 1 and rip version 2
d. none of the above
44) in the interior gateway routing protocol, a route is removed from the routing table after(在內(nèi)部網(wǎng)關(guān)路由選擇協(xié)議中，一個路由在多長時間之后從路由選擇表中刪除)？
a. three update periods
b. 60 seconds
c. five update periods
d. seven update periods
e. 90 seconds
45) which of the following is used to calculate metric in interior gateway routing protocol(下面的哪一個用于在內(nèi)部網(wǎng)關(guān)路由協(xié)議中計算度？ )
a. internetwork delay
b. bandwidth
c. load
d. reliability
e. all of the above
46) what is the maximum allowable number of hops in enhanced interior routing gatewayprotocol? (在增強(qiáng)內(nèi)部路由網(wǎng)關(guān)協(xié)議中，最多允許多少個跳計數(shù))？
a. 64
b. 224
c. 128
d. 232
e. 256
47) enhanced interior routing gateway protocol uses which of the following (增強(qiáng)內(nèi)部路由選擇網(wǎng)關(guān)協(xié)議使用下列的哪一種)？
a. link-state vector
b. diffusion update algorithm
c. distance vector
d. a and b only
e. b and c only
a.5 第5章答案
1) d。在連接不相似的網(wǎng)絡(luò)類型時要使用路由器。
2) a，d。組成路由選擇協(xié)議的兩個機(jī)制是選擇最佳路由和傳輸數(shù)據(jù)。
3) c。路由選擇表用來選擇最佳路由。
4) a ，b，d。路由選擇信息表包括目標(biāo)網(wǎng)絡(luò)地址和相關(guān)的數(shù)值，該數(shù)值提供了路由準(zhǔn)則： 跳、代價度或者下一個路徑。
5) c。路由選擇更新是用來維護(hù)路由選擇表的方法。
6) b，c。初始的數(shù)據(jù)包發(fā)送帶有目標(biāo)節(jié)點(diǎn)和m a c層(路由器的硬件地址)的網(wǎng)絡(luò)地址的數(shù)據(jù)包。
7) a，c，d。路由選擇協(xié)議的三個目標(biāo)分別是：準(zhǔn)確、快速收斂和低開銷。
8) d。收斂在所有路由器的路由選擇信息表同步時才發(fā)生。
9) b。因?yàn)槁酚稍诨ミB網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu)發(fā)生變化時將重新計算，所以動態(tài)路由協(xié)議是動態(tài)
10) a。靜態(tài)路由是人工輸入到路由選擇表中并且從來不被路由選擇協(xié)議更新的。
11) d。只有包含很少的路由器并且不經(jīng)常改動的小網(wǎng)絡(luò)適合于靜態(tài)路由，這是因?yàn)殪o態(tài)路由在互連網(wǎng)絡(luò)變動時要根據(jù)管理員的要求來更新每個路由器。
12) d。自治系統(tǒng)也可認(rèn)為是一個區(qū)域或者域。它是在較大互連網(wǎng)絡(luò)中定義的連續(xù)路由器集合；盡管它們共享路由選擇信息，但是它們不向區(qū)域外傳播信息。
13) d。默認(rèn)路由通常是靜態(tài)類型的路由，它可看作是最后求助的網(wǎng)關(guān)，在此所有非路由數(shù)據(jù)包進(jìn)行轉(zhuǎn)發(fā)以進(jìn)一步處理。
14) b。因?yàn)榫嚯x向量路由器復(fù)制它們鄰居的路由選擇表，更新它們并且轉(zhuǎn)發(fā)它們，所以它們使用了第二手信息。
15) a。無限計數(shù)問題是第二手信息產(chǎn)生的路由選擇循環(huán)。
16) d。破壞逆轉(zhuǎn)是水平分割的版本，它將“路由不可達(dá)”更新發(fā)送回路由器，從中可學(xué)習(xí)路由，這樣可避免路由選擇循環(huán)。
17) a。r i p是以前的距離向量協(xié)議和內(nèi)部網(wǎng)關(guān)協(xié)議，它的更新周期是3 0秒，最多1 5個跳計數(shù)。
18) d。i g r p是一個距離向量和內(nèi)部網(wǎng)關(guān)協(xié)議，最大網(wǎng)絡(luò)直徑是2 2 4 (即最多2 2 4個跳計數(shù))。
19) c。瞬時更新用來加速收斂。
20) d。管理員可調(diào)整用于路由選擇的加權(quán)值。
21) d。橋接、路由選擇和交換都可以從一個網(wǎng)段向另一個網(wǎng)段移動通信量。
22) c。路由選擇發(fā)生在網(wǎng)絡(luò)層上。
附錄a 自我測試題答案
23) c。度用來選擇最佳路由。代價和距離在確定最佳路由中可以為一些路由算法用作度尺度。
24) a。路由器通常具有路徑上目標(biāo)節(jié)點(diǎn)的網(wǎng)絡(luò)地址信息。
25) c。當(dāng)接收到數(shù)據(jù)包時，路由器會檢查目標(biāo)節(jié)點(diǎn)的地址。如果路由器不能向目標(biāo)地址發(fā)送數(shù)據(jù)包，那么路由器或者扔掉數(shù)據(jù)包，或者向默認(rèn)路由器發(fā)送數(shù)據(jù)包。
26) b。開銷通常和帶寬及c p u使用相關(guān)。精度與優(yōu)化的路由有關(guān)。
27) d。如果選擇不變的網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu)為網(wǎng)絡(luò)總體結(jié)構(gòu)，那么收斂就不是一個問題。答案
a、b和c都表示變化的網(wǎng)絡(luò)，它們都需要監(jiān)視收斂。
28) b 。i p路由選擇表允許路由器選擇數(shù)據(jù)包要采用的下一步路由。
29) c 。ip route命令包括數(shù)據(jù)包使用的路由器接口的i p地址。它也包括路由指向的網(wǎng)絡(luò)號和網(wǎng)絡(luò)的子網(wǎng)掩碼。
30) b。正確的命令是#ip route 86.0.0.0 255.0.0.0 35.3.3.4。答案a通過路由器x的接口向網(wǎng)絡(luò)a路由通信量。答案c通過路由器x的接口向網(wǎng)絡(luò)b路由信息量。答案d通過路由器y的接口向網(wǎng)絡(luò)a路由流量。
31) b。錯。要更改靜態(tài)表，需要有授權(quán)者的參與。
32) c。在混合類型的網(wǎng)絡(luò)中，非可路由數(shù)據(jù)包將路由到指定為最后求助的路由器的靜態(tài)路由器中。
33) b。在故障的情況下，分布的路由選擇協(xié)議提供了默認(rèn)容錯技術(shù)。
34) d。ip defa u lt命令需要一個網(wǎng)絡(luò)號。
35) b。距離向量路由選擇算法中的時效設(shè)置是針對所有的路由選擇信息。
36) b。對于較大的或復(fù)雜的網(wǎng)絡(luò)，如果停機(jī)周期足夠長，那么就會盡可能地減少與網(wǎng)絡(luò)穩(wěn)定性有關(guān)的問題(盡管不是在所有情況下都適用)。
37) b。作為有關(guān)度，鏈接狀態(tài)協(xié)議使用代價而不是路程段。
38) c。鏈接狀態(tài)協(xié)議中的泛洪就是指鏈接狀態(tài)路由器的鄰居接收到有關(guān)鏈接狀態(tài)數(shù)據(jù)包， 復(fù)制該數(shù)據(jù)包，然后將它轉(zhuǎn)發(fā)到網(wǎng)絡(luò)中的其余部分。
39) b. igp在網(wǎng)絡(luò)內(nèi)應(yīng)用到自治系統(tǒng)。
40) a。外部網(wǎng)關(guān)協(xié)議就是域間協(xié)議，因?yàn)樗鼈冊谟蜷g運(yùn)行。
41) b 。r i p有1 6個路程段的限制。
42) c 。r i p配置需要一個命令來啟用r i p，還需要一個命令來激活r i p接口。
43) b 。r i p鑒別命令僅僅可以和r i p的第2版本一起使用。
44) d。在7個更新周期之后，將從路由選擇表中刪除路由。在i g r p中，每9 0秒更新一次廣播。在三個更新周期之后，此時路由丟失，就是認(rèn)為路由不可到達(dá)。7個周期之后，路由被刪除。
45) e。在i g r p中，互連網(wǎng)絡(luò)延遲、負(fù)載、帶寬和可靠性都用來計算度值。
46) b 。e i g r p中用到的最大跳計數(shù)是2 2 4。
47) e。e i g r p將距離向量和d u a l一起使用，這改進(jìn)了收斂屬性。