BGP Fundamentals 3
Here you will find answers to BGP Fundamentals – Part 3
Question 1
Refer to the configuration shown. What could cause the BGP prefixes
from the 10.1.1.1 BGP peer to be absent from the routing table?
!
interface loopback0
ip address 10.10.10.10 255.255.255.255
!
router bgp 51001
synchronization
bgp log-neighbor-changes
bgp confederation identifier 51000
bgp confederation peers 51002 51003
network 10.0.0.0
neighbor 192.168.1.14 remote-as 51021
neighbor 192.168.1.18 remote-as 51022
neighbor 10.1.1.1 remote-as 51001
neighbor 10.1.1.1 next-hop-self
neighbor 10.1.1.1 update-source Loopback0
neighbor 10.2.2.1 remote-as 51002
neighbor 10.2.2.1 ebgp-multihop 255
neighbor 10.2.2.1 update-source Loopback0
neighbor 10.3.3.1 remote-as 51003
neighbor 10.3.3.1 ebgp-multihop 255
neighbor 10.3.3.1 update-source Loopback0
auto-summary
!
router rip
network 10.0.0.0
!
A. intraconfederation EBGP configurations error
B. autosummarization
C. ebgp-multihop issue
D. BGP synchronization
E. EBGP configurations error
Answer: D
Question 2
The core routers within a transit AS are running both IBGP and IGP.
The edge routers within the transit AS are using the next-hop-self
option to establish the IBGP sessions. What can be implemented to
improve the routing performance to all external prefixes?
A. enable route redistribution from BGP into IGP
B. disable BGP synchronization on all the core routers
C. enable CEF on all the core and edge routers
D. enable route redistribution from IGP into BGP
E. use route reflectors within the core
Answer: C
Question 3
What does the BGP synchronization rule prevent?
A. sub-optimal routing within a transit AS
B. routing black holes within a transit AS
C. routing loops within a transit AS
D. recursive routing lookups
E. scalability issues of redistributing BGP into an IGP
Answer: B
Question 4
Which one of these statements regarding intraconfederation EBGP sessions is correct?
A. Intraconfederation EBGP neighbors must be directly connected.
B. An intraconfederation EBGP session behaves like an IBGP session when propagating routing updates.
C. Member-AS numbers are removed when a router sends a BGP update over an intraconfederation EBGP session.
D. Updates from an intraconfederation EBGP neighbor are subject to the BGP split horizon rule.
E. Intraconfederation EBGP sessions must be established over loopback interfaces.
Answer: B
Question 5
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
Question 6
In the diagram, the customer is using BGP to connect to a single ISP
ober two permanent links. In this scenario, which input and output
prefix-list filtering is typically enabled on the ISP routers? (Choose
two)
A. ip prefix-list test-in permit 10.1.1.0/24 le 32
B. ip prefix-list test-in permit 10.0.0.0/8 le 32
C. ip prefix-list test-in permit 0.0.0.0/0
D. ip prefix-list test-out permit 10.1.1.0/24 le 32
E. ip prefix-list test-out permit 10.0.0.0/8 le 32
F. ip prefix-list test-out permit 0.0.0.0/0
Answer: A F
Question 7
Refer to the BGP configurations and the show outputs in the diagram.
What are two reasons why the 197.1.0.0/16 and 192.168.1.0/30 prefixes
are not in the BGP table of WGR1? (Choose two)
router bgp 1
no synchronization
bgp log-neighbor-changes
network 192.168.1.0
network 197.1.0.0 mask 255.255.0.0
neighbor 192.168.1.14 remote-as 22
auto-summary |
A. auto-summary is enabled.
B. The 197.1.0.0/16 prefix is not in the routing table of WGR1.
C. The 192.168.1.0/30 prefix is not in the routing table of WGR1.
D. The network 192.168.1.0 command defaults to the classful mask.
E. The aggregate-address 197.1.0.0 255.255.0.0 summary-only command
should be used instead of the network 197.1.0.0 mask 255.255.0.0
command.
Answer: B D
