rs-ccie面试视频题目

1、CCIEerview目录(2009 )Part Part Part Part Part Part Part Part Part PartPart1.2.3.4.5.6.7.8.9.10.11.IPv4 and IPv62RIP and EIGRP5OSPF8BGP13Multicast Routing20QoS27Switching32Security41Other49考生回忆题目53网上搜集911Part1.IPv4 and IPv61 问DHCP 获取地址的三个机制。？2 给了好几个ip dhcp pool，里面的network内容是一样的。有的POOL里没有DNS，有的POOL里没有de

2、fault-gateway，问用户为什么能得IP，但上不了网，Answer: If the users ip address is got from pool x , they can not acsernet becauseof no dns ; If the users ip address is got from pool y or pool z ,they can not acernet because of no default-gateway.s3 在一个subnetting network中，cisco提供了一个feature可以让每个subnet都能多一个可以使用的网络Answ

3、er:Ip subnet-zero4 ARP和RARP的作用是什么考者答：ARP : get mac according to ip addressRARP : get ip address according to mac address .5 让你分配一个掩码，如果网络里有no moren 50 hostAnswer ：926 what is the pure the fragment offsethe pakcet header?考者答：reame fragment packetsNote：Fragment Offset is a 13-bit fieldt specifies the

4、offset, in units of eight octets, fromthe beginning of the header to the beginning of the fragment.6 Because fragments mightnot always arrive in sequence, the Fragment Offset field allows theto bereassembledhe correct order.7 ip包哪些字段定义一个flowAnswer: source ip, destination ip , Protocol ID，tos .8 IPV4

5、包.给的图中有两处是空白的,问你少了哪两点？Answer: source ip and destination ip , tos ,total length29 What field in IP packet is prevented the packet from a router to router forever?Answer:TTL10解释水平分割Answer: split horizon is , when sending updates out a particularerface ,ot includenetworkst were learned from updates rec

6、eiveterface .split horizon prevents thesibility of routing loop. Split horizon is used by distance vector routing protocol in general.11as ？AS IS Autonomous systemAnswer: Eigrp 的 as，ProssBGP 的 as,These systems are routings，a set of routers running one or moreIGPs under a common administration.12arp和

7、rarp是单播，组播还是广播包 ？Answer: broadcast is used by request, unicast is used by reply .13R3R4R3 配置：no ip classlessip route 能不能上ernet？Answer :NO,it cannt . If you want to ac ip classless .sernet , we must change no ip classless to14根据给定情景选择一个acl，相当于问 acs-list 1 permit yy.yy.0.0 553和 acs-list 100 permit yy.

8、yy.0.0 55 区别Answer : 根据具体情况，自己选一个 acl。（讲解一下 ACL 匹配路由的方法）15描述了4句话，问是什么：第一个是说对进来的数据包有用第二个是和他匹配的数据包 FORWARD第三个是和他不匹配的数据包 drop第四个是可以和Answer: uRPF控制列表配合使用16在下列情况，ICMP发送那种类型的包Answer: 根据具体情况说明。分析如下：要么是 echo 和 echo reply1)echo 和 echo-replyecho 消息使用命令产生 icmp type：8，用来测试连通性。Echo-reply 用来回复echo 消息，ICMP type：0。

9、Router Advertisement和 Router SelectionIRDP协议（ICMP 路由器发现协议） 使用这两种ICMP消息，Router Advertisement为type9， Router Selection为type10，IRDP使主机能够发现本地网络中的路由器，并使用路由器的ip地址作为网关地址。Redirect2)3)Redirect 消息使用 type5，作用为：通知多路网关更好的路由器作为下一跳。Network Unreachable网络中主机去往目的地址比使用默认4)Network Unreachable 类型为 type3，有几种常见 code： 0:Net

10、work Unreachable 路由器路由表没有去往目的地址的路由条目1:Host Unreachable 数据已经发往最后一跳路由器，但 arp 查询不到目的主及的 mac2:Protocoreachable 数据包到达目的主机，但主机没有运行相应的上层协议3:Port Unreachable 数据包到达目的主机，但主机端口没有被4:Fragmenion Needed andt Fragment Flag Set 数据包超过 mtu 值但设置了不能分片。Time Exceeded ICMP MessageTime Exceeded 使用 icmp type 11。作用是通知主机发送数据包的

11、数据包由于超时（ttl=0）被丢弃。5)17根据3个说明说出这个是描述ipv6里面一个什么概念？Answer: IPV6 neighbor discovery protocol.注意 3 个描述，如果描述是：代替 arp，无状态自动配置，路由重定向，那描述的协议就是 IPv6 NDP418IPv6的solicited-node multicast address的作用是什么？Answer: 1,replacement of the arp protocol2,duplicate address detection19whats the role of link-address in Ipv6,

12、is it nesary, why?考者答：The unicast link-local address is scoped and is usely betn nodes connectethe same local link. The link-local address is used by several IPv6 mechanisms, such asNeighbor Discovery Protocol (NDP), RIPng.ospfv3 etc. Link-local addresses are only forlocal-link scope and must never

13、be routed betn subnets within a site. When an IPv6stack is enablea node, one link-local address is automatically assigned to eacherface of the node at boot time. link-local prefix FE80:/10 is used.20Which pros uses ICMP messages and solicited-node multicastaddresses to determine the link-layer addre

14、ss of a neighbor on the samenetwork (local link), verify the reachability of a neighbor, and track neighboring routers?考者答：The IPv6 neighbor discovery pros;Note:usingicmpv6135neighborsoliciion(NS)andicmpv6136neighboradvertisement(NA)21NTP怎么度量距离可靠源的距离？答：ntp uses the concept of a stratum to describe h

15、ow many NTP hops away a machine is from an authoriive time source.Part2.RIP and EIGRP1.跑 rip问 R1 到 R2 几跳 ？5Answer: 1 hop （仔细审题，有可能是 2 hop）2.一个路由表，有 3 条，分别从 ri择哪调走pf，eigrp 学过来的，到达相同目的，问路由选Answer: If eigrp isernal route, then select eigrp . If eigrp is external route ,then selectospf . it will select

16、the entry which is learned from the route protocol with the lowest AD .3.ripv2 使用什么决定路径Answer:RIPV2 use the hop as its metric.when the route through a router it will ade4.Rip v1 不连续子网，有图，具体不清楚（但肯定是不连续子网），问解决方法Answer:1 add secondary address 2 change rip v1 to rip v23change classfull routing protocol

17、to classless routing protocol.5.EIGRP 非等价负载问题 ，如图示：Question:if we set the variance 2,how will router A choose the path to 172 network?Answer: if the variance is 2, eigrp will choose B and C as its best path to get to 172,6.EIGRP 1-2 1 上 ip nei1 上看不到 22 上看到 1sho ip eigrpnei2 上地址 和第二地址 show ip ei没邻居能接

18、受 1 的2 有邻居2 有第二地址1 没有O 包但是 1 不能 ,可能问：为什么？Answer: R2 receives and accepts R1o packets,but R1 cant 。This happens becauseEIGRP updates always use the primary IP address of the outgoingerface as the sourceaddress. Change the prithis problem.ddress on R1 to match the R2 primary subnet to resolve7.第三题，eig

19、rp 的，算 fd，rd，fsser 的那个6差不多就是这样的，里面都是空的，要求全部写上好像还多问了，fs 和sucor8.r1 和 r2 之间是一个 sw，sw 运行了 STP 协议，r1 和 r2 运行 eigrp，当 r1 和 sw 之间的链路 down 掉，r2 怎么获知 r1 的邻居 down 掉 ？r1r2There is a SW betnr1 and r2,SW is running STP protocol,R1 and R2 runn r1 and SW is down, how does R2 know r1s neighborEIGRP,when the link b

20、et is down?答：when eigrps holdtimeexpires ,R2 knows neighdown9.是 eigrp for frame,hub 是多点，spoke 是点到点，邻居建不起来，为什么Answer:because broadcast keyword doesnotbeconfigured，wecsouseneighbor to resolve the problem .10. EIGRP 的四种 METRIC 类型Answer:Bandwidth,Delay,Reliability,Load11. traffic-share balanced 命令是什么意思？

21、Answer: when configuring eigrp Unequal-Cost Load Balancing and traffic-share balanced ,the router is performing unequal-cost, packet load balancing. This corresponds to the7approximay variance of the metrics of these two paths balancedShare inverselyproportional to metricminAll traffic shared among

22、metric paths12. 是 eigrp for frame,hub 是多点，spoke 是点到点，not work，为什么 就 R1 R2 ?应该是问为什么 R2，R3 为什么看不到互相的路由 topology“R2R1R3”Answer: because split horizon is default enableframe-relay multipoerface.13. 还有在配 EIGRP 的时候（frame-relay 的 NBMA）命令router(config-router)#neighbor 29 是什么意思呢？Answer: eigrp sendo packet to

23、 nei 29 with unicast and without multicast.because broadcast is not enabletheerface or passived .14. ip bandwidth-percent eigrp 200 20 是什么意思?Answer: in as 200 , eigrp routing protocol can use 20% of configured bandwidth of the erface at most.Answer1 : 200 is parameter of eigrp as number , 20 is the

24、percentage of the configuredbandwidtht eigrp can use , by default , eigrp may use up to 50 percent of thebandwidth of anerface or suberface .15. 问了 ospf 和 eigrp 的 ADAnswer:Ospf 110Eigrp 5summary route ,90ernal route,170 external route16. SIA可能是问的处在 SIA 状态时，路由器的反应和处理过程Answer: The router has to get al

25、l the reps from the neighbors win outstanding querybefore the router calculates the sucsor information. If any neighbor fails to reply to thequery within 3 minutes by default, the route is SIA, and the router resets the neighborrelationship with the neighbort fails to reply.Part3.OSPF1.问在下图中，area 0

26、和 area1 （NSSA）和 area 2 中类型的 LSA 和路由？Answer:Area 0： LSA1235Area 1(if NSSA ) ： LSA 1237Area 1(if totally NSSA) ：LSA 123(default only)78Area 2 : LSA 1 2 3 4 52.描述 stub 区域能出现什么 lsa,注意,要回答 nssa 和 totle stub,最好说明为什么Answer:IfStubIfTotally stub NssaTotally nssalsa 1,2,lsa3(default addition) lsa 1,2, lsa3(de

27、fault only)lsa 1,2,3,7lsa1,2,7,lsa3(default only)3.问在哪台设备上可以看到下面的显示的：用这个命令：show ipf neighbor给了几个 Neighbor 列表Answer: the fourth router ( from left to right )4.在OSPF 网络中建立 nssa 区域的 area 1 nssa default-information-originate 中参数default-information-originate 是什么意思呢？Note：Thisd is usean OSPF ABR or an OSPF

28、 ASBR to generate an OSPF NSSAexternal type 2 default routeo an NSSA. A default route does not need to be defined whenusing thisneeds to be configured.an ABR. If thisd is configurean ASBR, then a default route5.给了 ospf 的 3 个区域 area 0 1 2 问在那个类型的路由器上汇总最好上图：area0 、1、2，问对 area1 中的路由作汇那里作好？如 R2 和 R5 间建有

29、 virtual-link，汇总作在 R2 和 R5 上；如无 virtual-link，则在 R2 上作；Answer: R2 is the best .6.如图：R1 上有个 6 接口，做了 redistribute connect 动作R3 上作了 RIP redistribute要求。Describe the routes/LSAo OSPF 的动作。he area 0 and area 19Answer: Area 0Area 11,2,3,51,2,3,77.OSPF show ipf nei 输出的对不（考生回答说：是对的问 WHY 了）Answer: it is correct

30、. Because full is betDRother and DRother.n DR/BDR and DRother，2way is betn8.R1-R2-R3,都在一个 OSPF 区域中,R1R3 之间虚链路,问:虚链o 包.是否交换Answer:os are exchanged when neighbore adjacence . while the virtual link is up, noos are exchanged。9.Answer: virtual-link need to be configured in router r2 , Because the ospf r

31、equire areasdirectly connet to the backbone area 0 .10. ospf 的默认路由 metric 如何计算Answer:108/bandwidth of theerface(kbit)11. 在 abr ,什么样的 lsa 会被 blocked ,不进入到 stub areaAnswer:LSA4 and LSA512. 给你一个图10运行 ospf，都在区域 0 里，问 A 到 E 怎么走 ?Answer: 应是考域内优于域间，域间优于域外。13. On the po-to-poserial, how the OSPF select DR?A

32、nswer: If ospf network type is po-to-poor po-to-multipo，dr is not need .If ospf network type is broadcast or nbma , dr is need . Dr is the router with the biggestpriority. In a tie, the biggest router_id is the tie-breaker.14. ospfV2 和 ospfv3 能否在同一接口同时启用Answer: Yes.15. 问：按照以上的配置，R1和R2的邻居关系能不能full，R1

33、和R3的邻居关系能不能full，并解释你的。R1和R2间能full；R1和R3间不能full；ospf配，邻居建立不起来。erface不在同一个网段上且地址duplicate导致o的参数不匹Answer : R1 and R2 can enter full se . but R1 and R3 can not enter full se becausethe netmask is not the same .16. Does filtering an inbound OSPF prefix widistribution list removet prefixfrom the routing t

34、able of neighboring OSPF routers?Why or why not?11answer: No. While the route is not installedand is flooded to OSPF neighbors.he local routing table, the LSA is not filtered17. Each router have partial map of network, its belong a family of IP routingprotocols, whats the route protocol from this de

35、scribe?考者答：link-se protocol for exle ospf18. name 4 ospf area type答：看题目问的是什么，如果从上面看，应该答：stub、NSSA、backbone，standard area/There are several OSPF area types: standard, backbone, stub, totally stubby, and NSSA.19. What type of router for eigrp neighbor ?R2#show ip eigrp nei detailIP-EIGRP neighbors for

36、 pros 10Hold Uptime (sec)12 00:01:07HAddresserfaceSRTT(ms) 24RTOQCnt 0SeqNum 70Se2/2200Ver12.4/1.2, Retrans: 1, Retries: 0Stub Peer Advertising ( CONNECTED SUMMARY ) RoutesIP-EIGRP neighbors for pros 100Hold Uptime(sec) 11 00:01:30HAddresserfaceSRTT(ms) 43RTOQCnt 0SeqNum 30Se2/3258Ver12.4/1.2, Retra

37、ns: 0, Retries: 0考者答：eigrp stub router.12Part4.BGP1.how bgp synchronization affected the route to /24.（上图）Answer: 根据下面的 BGP 同步的概念，修改某些单词。2.what is the BGP synchronization ?Answer: Before a rouearned from an IBGP neighinstalledo the IP routing tableor is advertised to a BGP peer, the route mustbe kno

38、wn via IGP.3.Q:问描述的是什么这个协议用的 TCP 179 端口有 peer-group，有 keepalive，有 established,Answer : It describes the pros how to establish bgp neighbor.4.两个路由器，直连，建立 EBGP，使用了一条 nei 命令，问你为啥不通Answer:Ifneighconfiguredwithloack,youmustaddtwod(update-source and ebgp-multihop)5.Answer: R1 will select R4 to , because t

39、he med received from R4 is the smallern from R2.136.bgp 放环技术有哪几种？AS 间，as-path （as-sequence/as-set）AS 内，split-horizion,AS 内，RouteReflector （originator-id and cluster-list-id） AS 内，confederation(as-confed-set/as-confed-sequence)仔细审题，看它问的是什么？如何防环还是防环技术有哪些？Answer: In a as , bgp use ibgp forward rule to

40、protect loop. Ibgp forward rule ist a routereceived from an ibgp neighbor will not advertise to another ibgp neighbor .Betn as ,bgp use as-path to protect loop . A router discards the route received when his own asnumber is found in as-path .7.which BGP attribute will influence inbound flow?Answer:A

41、S_PATHandMulti_Exit_Disc(MED)and origin8.Local_Pref is influence inbound routing and outbound flow ？Answer: Influence outbound flow9.what about the BGP AdministrationDistance ?Answer:ernal BGP is 200 ,External BGP is 20,Local BGP is 20010. BGP neighbors building proAnswer:s?Idle Se/Connect Se/Active

42、 Se/ OpenSent Se/ OpenConfirm Se Established SeNote：BGP always beginshe Idle se , initializes a TCP connection to the neighbor, andchanges its se to Connect.If the TCP connection icsful, the BGP prossends an Open message to the neighbor, and transitions to the OpenSent se.Whenanother Open message is

43、 received, no error exists . the se is changed to openconfirmWheneepalive message is received, the se is changed to Established.his se,the BGP peer connection is fully established and the peers can exchange Update.11. 1 台 BGP 路由器和 4 个 IBGP 需要的多少条 neighborAnswer：d?If full mesh ,it is 8(4*neighbor rem

44、ote-as + 4*neighbor update-source ).If route reflector, reflcetor is 12(4*neighbor remote-as + 4*neighbor update-source + 4*neighbor route-reflector-cnt) or 11(4*neighbor remote-as + 4*neighbor update-source+ 3*neighbor route-reflector-cnt)12. what is automic_aggregate?Answer: ATOMIC_AGGREGATE is a

45、well-known discretionary attributet is used toalert downstream routerst a loss of path information has occurred1413. 路由器选哪条路Answer: 应写左面的，根据图来实际回答。14. AS 5 的 full as-path 是什么?Answer: 3 115. R1(AS1)-R2(AS2)-R3(AS2)R4(AS2),R1 在 AS1,R2,R3,R4 在 AS2,R1 和R2 建 EBGP，R2 和 R3 IBGP,R3 和 R4 IBGP,有一条路有从 R1 传给 R2

46、,问这条路有会不会在 R4 上出现,如果不会,怎么解决.Answer：The route wont advertise to R4 . We can use ibgp full mesh peering, orroute-reflector, or confederation to resolve .16. AS2 的路有器把路由发给 AS1 左边来的 WEIGHT 61 并且 LP150,右边 WEIGHT62，问 AS1 选哪条路去 AS2Answer: the left router will select left side to as2 because bigger weight,

47、the right router will select right side to as 2 because of bigger local prefence.17. 选路，问到走哪条，自己选，我选的是515Answer: R1-R3-R518. 好像是问的 BGP 的团体属性会不会影响最佳路径的选择Answer: YES if you use bgp cost community , but this st bgp bestpath costcommunity ignore .s skipn you can use19. sh ip route bgp描述一下看到的路由r1#sh ip r

48、oute bgp/24 ibnetted, 1 subnetsB 20/0 via , 00:00:15Answer: 是以前说的。20. Multi-exit discriminator、AS-Path、Weight、Local_preference，问你 followingsequence（就是排下序）Answer:Weight-Local_pref-as-path-med21. Local_preference 的作用范围（题目意思大概是这样的）Answer: Local_preference is a well-known discretionary attribute inside

49、a AS; it is not passed to outside of a ASt is usely22. Weight 的作用范围Answer: weight is a Cisco-specific BGP attributet apps only to a single Routerand not advertise to any otheer23. No advertise the routed but router C can received it, how resolve it ?/ 题意可能是说 A 通告一条带有 no-advertise community 的路由给 B ，问

50、 C 能否收到 ？如何解决 ？Answer: Not advertise to any BGP peers, you can set the no-export or local-as to solve ithis case.24. 题：router bgp 500016neighbor remote-as 5000neighbor activateneighbor route-map AAA out这里还有一句 neighbor 命令不记得了 route-map AAAmatch ip add 1setmunity 1 100问：Why cant the router send the co

51、mmunity to other routers ?答： the neighbor.xmunity is not ied.Note:有说 acs-list 1 没有定义导致无法通告，实际如果 acs-list 1 未定义，相当于acs-list 1 permit any,所以不是 acl 未定义的原因25. bgp community no-advertise还是no-export不记得了。问这个属性Answer ：no-advertise : Routes received carrying this value cannot be advertised at all, to either

52、EBGP or IBGP peers.No-export : Routes received carrying this value cannot be advertised to EBGP peers or, ifa confederation is configured, the routes can be advertised outside of the confederation. Local_as 自己组织一下。作用26. 具体忘了怎么描述的，问S 路有条目前的S什么意思？答：the router ippressed because of aggregate , is not ad

53、vertised to any nei .这条路由被聚合路由抑制掉了；不会被通告出去27. router bgp 19Neig um-prefix 1000这句命令作用？答：Thisd allows you to configure aum number of prefixest a BGProuter is allowed to receive fromer. It adds another mechanism (in addition todistribuists, filter lists, and route maps) to control prefixes received fro

54、mer.28. 问你 bgp suppress 什么意思?答：suppress some more-specific routes of the aggregate not to be advertised out29. whats the role of community attributehe bgp route?考者答：1 , Community attribute is a parameter set of bgp routes,it can be looked as tag2, /再提一句, cost community 能用来选路。t describea common chara

55、cter of a30. BGPconfig was given with route-map and what will happen to route Router bgp 1yy17No auto No synNei remote 111Nei updaNei o0munityNei route-map A outRoute-mapr 10Match ip add acl 12Set community no-advertiseAcs-list 12 per 答：the route can be received by bgp nei , but nei wouldadvertise t

56、he route to any bgp neighbor because of communit no-advertise .not31. 一个bgp show runRouter bgp net nei remot 111 nei up l0nei route-map LOCAL-AS outnei munityroute-map LOCAL-AS per 10 match ip add 10set community local-as route-map LOCAL-AS per 20 ace 10 per 问网段 会发生什么答：the route can be advertised to

57、 nei , but nei advertise the route to its ebgp neighbor or confederation ebgp neighbor；cannot32. 问一个怎么样的属性，能让路有不通告给任何的peer？答：community ：no-advertise33.Router bgpNet Nei Nei NeiNei54 remote 20 up lo 0 munity route-map con out18Route-map con per 10 Match ip add 10Set community no-advertiseAcs 10 per 5

58、4问：按照以上的配置，54 这条路由会怎么样？答：the route 54 will be advertised to bgp nei , but nei will notadvertise the route to any bgp neighbor because of community no-advertise .34. Whats pure of CIDR?考者答：CIDR moves way from the traditional IP classes (Class A, Class B, Class C, and so on). In CIDR , an IP network i

59、s represented by a prefix, which is an IP address and some indication of the length of the mask.CIDR allows routers to minimize thety of routing information to improve bothaddress space utilization整理者答：CIDR washeernet.roduced to improve boddress space utilization and routingscalabilityheernet. It wa

60、s needed because of the ragrowth of theernet andgrowth of the ip routing tables heldheernet routers.Classlesserrouting35. 什么情况会使 BGP 停止在 IDLE 状态Answer : “BGP always beginshe Idle se, in which it refuses allingconnections.The BGP pros initializes all BGP resour, starts the ConnectRetrytimer, initiali