Cisco 642-661 Exam - Cheat-Test.com

Free 642-661 Sample Questions:

1.What is a key benefit of implementing the bgp dmzlink­bw command?
A.establishes a secure BGP link between eBGP and iBGP peers
B.enables the unequal cost path load balancing feature for external BGP links
C.allows BGP to use link bandwidth as a metric when computing best route selection
D.increases BGP security by dynamically allocating community strings to eBGP routes
Answer: B

2.What are two purposes of the BGP scan­time command? (Choose two.)
A.to tune the BGP process which walks the BGP table and confirms the reachability of next hops
B.to allow faster detection of downed BGP peers
C.to improve BGP convergence time
D.to tune the BGP update interval
E.to decrease the effects of unstable routes by increasing the route suppression time
Answer: A, C

3.Which command is used to configure the external, confederation­wide AS number?
A.router(config)#router bgp {as­number}
B.router(config­router)#bgp confederation peers {as­number}
C.router(config­router)#bgp confederation identifier {as­number}
D.router(config­router)#bgp cluster­id {as­number}
E.router(config­router)#neighbor {ip address} remote­as {as­number}
Answer: C

4.When creating iBGP multipaths which three criteria must be met by multiple paths to the same destination? (Choose three.)
A.Router IDs must be the same on all routers.
B.Each destination must have a different next­hop address.
C.The destination AS­number must be different for each destination.
D.Multi­exit discriminator attributes must be the same on all paths.
E.Interior Gateway Protocol distance must be identical on each path.
Answer: B, D, E

5.Why can using the ip tcp path­mtu­discovery command improve BGP convergence?
A.Single packet sizes in TCP sessions are limited.
B.Smaller MSS sizes may reduce BGP convergence times.
C.BGP is allowed to use a larger TCP window size.
D.BGP is enabled to fragment its large update packets.
E.The BGP memory requirements on routers are reduced.
Answer: B

6.What state will a BGP session move to immediately after the router sends a BGP Open message to its neighbor?
A.active
B.OpenConfirm
C.OpenSent
D.established
E.idle
Answer: C

7.Which two of these statements about hierarchical route reflectors are correct? (Choose two.)
A.A route reflector can be a client of another route reflector.
B.Each cluster within the hierarchy can only contain one route reflector.
C.The hierarchy can be as deep as needed.
D.A route reflector can have clients in different clusters.
E.Hierarchical route reflectors are set up using three levels (access, distribution, and core layers).
Answer: A, C

8.What can cause a single sourced iBGP route not to be selected as the best route?
A.The BGP MED is 0.
B.The BGP next­hop is unreachable.
C.The BGP origin is incomplete.
D.The BGP weight is 0.
E.The BGP local preference is 0. F.BGP synchronization is disabled.
Answer: B

9.What are three characteristics of the local preference BGP attribute? (Choose three.)
A.It is stripped in outgoing EBGP updates except with confederation peers.
B.It is used to influence the incoming traffic.
C.Its default local preference is 32768.
D.It is used to select routes with equal weight.
E.It can be used to ensure an AS­wide route selection policy.
F.It is a Cisco­only BGP path attribute.
Answer: A, D, E

10.Which two of the following are true regarding the BGP Prefix­Based outbound route filtering feature? (Choose two.)
A.IP multicast routes are not supported.
B.Outbound route filtering is configured only on a per­address family basis.
C.Outbound route filtering can be configured for either iBGP or eBGP sessions.
D.The outbound route filter can be defined in a Prefix list, Distribute list or Access lists.
E.Outbound route filtering is more effective when a distance vector IGP is used.
Answer: A, B

11.Which configuration will enable the R1 router in the AS51003 sub­AS (member­AS) as a route reflector with neighbors 10.1.1.1 and 10.2.2.2 as its route­reflector clients?
A.! R1 router bgp 51003 bgp confederation identifier 55111 bgp confederation peers 51001 51002 neighbor 10.1.1.1 remote­as 51003 neighbor 10.2.2.2 remote­as 51003 neighbor 10.1.1.1 route­reflector­client neighbor 10.2.2.2 route­reflector­client
B.! R1 router bgp 51003 bgp confederation identifier 55111 bgp confederation peers 51001 51002 neighbor 10.1.1.1 remote­as 51001 neighbor 10.2.2.2 remote­as 51002 neighbor 10.1.1.1 route­reflector­client neighbor 10.2.2.2 route­reflector­client
C.! R1 router bgp 55111 bgp confederation identifier 51003 neighbor 10.1.1.1 remote­as 51003 neighbor
10.2.2.2 remote­as 51003 neighbor 10.1.1.1 route­reflector­client neighbor 10.2.2.2 route­reflector­client
D.! R1 router bgp 55111 bgp confederation identifier 51003 neighbor 10.1.1.1 remote­as 55111 neighbor
10.2.2.2 remote­as 55111 neighbor 10.1.1.1 route­reflector­client neighbor 10.2.2.2 route­reflector­client
Answer: A

12.Which BGP configuration option is designed to reduce router processing load caused by unstable routes?
A.neighbor {ip­address} maximum­prefix {number}
B.bgp dampening
C.no sync
D.bgp deterministic­med
E.sync
F.bgp scan­time
Answer: B

13.How can you prevent multihomed customers with connections to two service providers from acting as a transit AS?
A.Enable BGP synchronization on all the customer routers.
B.Use MED to influence the inbound traffic from the ISPs.
C.Use static routing to the ISPs.
D.Use an AS­path access­list to filter the BGP updates to the ISPs.
E.Use conditional advertisements when sending BGP updates to the ISPs.
Answer: D

14.In the diagram, the customer is using BGP to connect to a single ISP over two permanent links.
In this scenario, which input and output prefix­list filtering is typically enabled on the ISP routers? (Choose two.)

A.ip prefix­list test­in permit 10.1.1.0/24 le 32
B.ip prefix­list test­in permit 10.0.0.0/8 le 32
C.ip prefix­list test­in permit 0.0.0.0/0
D.ip prefix­list test­out permit 10.1.1.0/24 le 32
E.ip prefix­list test­out permit 10.0.0.0/8 le 32
F.ip prefix­list test­out permit 0.0.0.0/0
Answer: A, F

15.Which three conditions can make a transit autonomous system unable to forward packets from one neighboring autonomous system to another neighboring autonomous system? (Choose three.)
A.sync enabled
B.bgp next­hop not reachable
C.no full­mesh IBGP and not using route reflectors or confederations
D.non­directly connected IBGP neighbors
E.non­directly connected EBGP neighbors
F.EBGP to IBGP route redistribution configuration errors
Answer: A, B, C

16.Based on the following show ip bgp neighbors 2.2.2.2 output, which two statements are true? (Choose two.)R1#show ip bgp neighbors 2.2.2.2BGP neighbor is 2.2.2.2, remote AS 102, internal linkIndex 1, Offset 0, Mask 0x2BGP version 4, remote router ID 66.0.0.1BGP state=Established, table version=1, up for 00:14:52Last read 00:00:52, hold time is 180, keepalive interval is 60 secondsMinimum time between advertisement runs is 5 secondsReceived 233 messages, 0 notifications, 0 in queueSent 206 messages, 0 notifications, 0 in queuePrefix advertised 0, suppressed 0, withdrawn 0Connections established 17; dropped 16Last reset 00:15:02, due to User reset18 accepted prefixes consume 576 bytes, maximum limit 20Threshold for warning message 80%0 history paths consume 0 bytes
A.R1 has accepted 20 prefixes from the 2.2.2.2 IBGP neighbor.
B.R1 generated a warning message to the router's console after the 2.2.2.2 IBGP neighbor sent 16
prefixes to R1.
C.R1 generated a warning message to the router's console after the 2.2.2.2 IBGP neighbor sent 15
prefixes to R1.
D.R1 will drop its neighbor relationship to the 2.2.2.2 IBGP neighbor if 2.2.2.2 sends two more additional prefixes to R1.
E.R1 will drop its neighbor relationship to the 2.2.2.2 IBGP neighbor if 2.2.2.2 sends three more additional prefixes to R1.
Answer: B, E

17.Which of these situations best describe when to use the AS number translation feature?
A.All single­homed customers are using public AS numbers.
B.All single­homed customers are using private AS numbers.
C.All multihomed customers are using public AS numbers.
D.All multihomed customers are assigned different AS numbers from different ISPs.
Answer: D

18.Which two configuration commands will complete the BGP configuration on R1 so it will conditionally announce the 172.0.0.0/8 prefix to R4 via BGP? (Choose two.)
hostname R1!!output omitted!1. ______!router bgp 65001neighbor 172.16.1.1 remote­as
65001neighbor 2.2.2.2 remote­as 65001neighbor 4.4.4.4 remote­as 387!2.

A.2. network 172.16.0.0auto­summary
B.2. network 172.0.0.0 mask 255.0.0.0
C.1. ip route 172.0.0.0 255.0.0.0 null0
D.1. ip route 172.0.0.0 255.0.0.0 null0 255
E.1. ip route 172.0.0.0 255.0.0.0 172.16.1.1
F.2. aggregate­address 172.0.0.0 mask 255.0.0.0
Answer: B, E

19.The neighbor {ip­address} maximum­prefix {maximum number} command prevents which router condition?
A.frequent BGP session resets
B.routing instability
C.asymmetric routing
D.CPU and memory exhaustion
E.route flaps
Answer: D

20.Which three actions are prerequisites to configuring the BGP link bandwidth feature? (Choose three.)
A.enable BGP synchronization
B.configure BGP multipath first
C.configure eBGP multihop on eBGP peers
D.enable Cisco Express Forwarding on the router
E.enable BGP community propagation between link bandwidth advertising routers
Answer: B, D, E

21.Which two statements about a transit AS are correct? (Choose two.)
A.A transit AS has eBGP connection(s) to only one external AS.
B.Routes between ASs are always exchanged via eBGP.
C.A transit AS uses an IGP like OSPF or ISIS to propagate the external networks within the transit AS.
D.Core routers within a transit AS normally use default routing to reach the external networks.
E.iBGP sessions can be established between non directly connected routers.
Answer: B, E

22.Based on the network diagram shown in the exhibit, what is the correct configuration on the customer edge router used to conditionally announce the customer networks to the ISP?

A.router bgp 65001 ! neighbor commands not shown network 192.168.8.0 mask 255.255.252.0 ! ip route
192.168.8.0 255.255.252.0 192.168.8.33
B.router bgp 65001 ! neighbor commands not shown aggregate­address 192.168.8.0 255.255.252.0
summary­only ! ip route 192.168.8.0 255.255.252.0 192.168.8.33
C.router bgp 65001 ! neighbor commands not shown network 192.168.8.0 network 192.168.9.0 network
192.168.10.0 network 192.168.11.0 ! ip route 192.168.8.0 255.255.255.0 null0 ip route 192.168.9.0
255.255.255.0 null0 ip route 192.168.10.0 255.255.255.0 null0 ip route 192.168.11.0 255.255.255.0 null0
D.router bgp 65001 ! neighbor commands not shown aggregate­address 192.168.8.0 255.255.252.0
summary­only ! router ospf 1 network 192.168.8.0 0.0.3.255 area 0
E.router bgp 65001 ! neighbor commands not shown aggregate­address 192.168.8.0 255.255.252.0 ! ip route 192.168.8.0 255.255.252.0 null0
Answer: A

23.Refer to the partial topology diagram shown.Service Provider 1 (SP1) assigned the customer an AS number of 65275. Service Provider 2 (SP2) assigned an AS number of 65745 to the customer. The customer decides to use AS 65275 internally.Which of the following is the correct partial router configuration to cause updates from CR1 to SP1 to report a source AS of 65275, while updates from CR2 to SP2 report the source AS of 65745 in addition to AS 65275?

A.!CR1router bgp 65275neighbor 1.1.1.1 remote­as 65274neighbor 10.1.1.2 remote­as 65275!CR2router
bgp 65275neighbor 2.2.2.2 remote­as 65732neighbor 2.2.2.2 local­as 65745neighbor 10.1.1.1 remote­as
65275
B.!CR1router bgp 65275neighbor 1.1.1.1 remote­as 65274neighbor 10.1.1.2 remote­as 65275!CR2router
bgp 65745neighbor 2.2.2.2 remote­as 65732neighbor 2.2.2.2 local­as 65745neighbor 10.1.1.1 remote­as
65275
C.!CR1router bgp 65275neighbor 1.1.1.1 remote­as 65274neighbor 1.1.1.1 local­as 65745neighbor
10.1.1.2 remote­as 65275!CR2router bgp 65275neighbor 2.2.2.2 remote­as 65732neighbor 2.2.2.2
local­as 65745neighbor 10.1.1.1 remote­as 65275
D.!CR1router bgp 65275neighbor 1.1.1.1 remote­as 65274neighbor 10.1.1.2 remote­as 65275!CR2router bgp 65745neighbor 2.2.2.2 remote­as 65732neighbor 2.2.2.2 local­as 65275neighbor 10.1.1.1 remote­as
65275
Answer: A