BGP

Description

BGP Interview Questions & Answers Vol 1.0

Questions 100

Check the complete list of questions:

1. Can router on different subnet become BGP neighbour?
2. What is the difference between eBGP multihop and TTL security?
3. Which protocol and the port number does BGP use for neighborship?
4. How do I configure BGP?
5. What is the use of BGP best path community ignore command?
6. How do I configure BGP with the use of a loopback address?
7. What is the order of preference of attributes when applied to one neighbour in BGP?
8. What does a next-hop of 0.0.0.0 mean in the show IP BGP command output?
9. What are the well-known communities of the BGP community attribute?
10. How does BGP behave differently with auto-summary enabled or disabled?
11. What formats can I use to configure the BGP community attribute?
12. When and how should I reset a BGP session?
13. Is there any special configuration needed on PIX/ASA to allow BGP sessions through it?
14. What is an autonomous system number (ASN) and how do I obtain one?
15. What is the BGP path selection criteria?
16. What is the difference between always-compare-med and deterministic-med?
17. Do internal BGP (iBGP) sessions modify the next-hop?
18. Do external BGP (eBGP) sessions modify the next-hop?
19. Do external BGP (eBGP) sessions between confederations modify the next-hop?
20. In external BGP (eBGP) sessions, which IP address is sent as the next hop?
21. Does the route reflector change the next-hop attribute of a reflected prefix?
22. How can I announce a prefix conditionally to one ISP only when I lose the connection to my primary ISP?
23. How can I configure BGP to provide load sharing and redundancy in my network?
24. How much memory should I have in my router to receive the complete BGP routing table from my ISP?
25. What are the benefits of configuring BGP peer groups?
26. Why do I see the same route twice from the same peer in BGP?
27. What is synchronization, and how does it influence BGP routes installed in the IP routing table?
28. How do I know which Cisco IOS software release supports a particular BGP feature?
29. How can I set the Multi Exit Discriminator (MED) value on prefixes advertised to external BGP (eBGP) neighbours to match the Interior Gateway Protocol (IGP) next hop metric?
30. What is the default BGP ConnectRetry timer, and is it possible to tune the BGP ConnectRetry timer?
31. What does r RIB-Failure mean in the show ip bgp command output?
32. How can I redistribute internal BGP (iBGP) learned default-route (0.0.0.0/0) route into EIGRP/OSPF/IS-IS?
33. How can I filter all IP routes advertised to a BGP neighbour except the default route 0.0.0.0/0?
34. Is it possible to track an interface and change the route availability?
35. How does IP RIB Update allocate memory?
36. What is the command to see IPv6 BGP neighbours?
37. In regards to the removal of the static route “ip route 10.10.0.0 255.255.0.0 Null0”, does no auto-summary in BGP cause all subnets of 10.10.0.0 to be advertised?
38. Why are there no statistic results when I use the debug bfd events and debug bfd packets commands?
39. Can I run two BGP process on a single router?
40. Difference between hard reset and soft reset in BGP?
41. What are different BGP message types
42. What are various BGP states?
43. Which command is used to disable BGP neighborship?
44. What are the values of keepalive and Dead timers in BGP?
45. How many public and private AS numbers are there?
46. BGP Route selection criteria?
47. Does the router have to be restarted after a new BGP Neighbor Maximum Prefix is configured?
48. Is there a command to check the advertised routes along with the prepend of the AS-paths?
49. How does neighbour soft-reconfiguration inbound command function?
50. What is the difference between when a route is injected in BGP via redistributing command or a network command?
51. How do I verify Layer 4 forwarding summary information?
52. What are IGPs and EGPs and why are they different?
53. Name several path attributes and their function.
54. Why is there a problem with iBGP in large networks? How can this problem be solved?
55. Name BGP path attributes to control incoming and outgoing traffic
56. My BGP is showing 0.0.0.0 as router-id; what could be the possible reason?
57. If my BGP neighbour is stuck in an idle or active state, what should I do?
58. Explain BGP recursive lookup and site of origin (SoO).
59. What do you understand by BGP split-horizon rule?
60. Describe BGP communities. Name well-known communities.
61. Can I use BGP instead of any IGP?
62. Types of a BGP routing table?
63. What is route reflector and why it is required?
64. What is no-synchronization rule?
65. What are Default BGP timers?
66. In Multihoming scenario, if the primary link gets fail, after how long traffic will be shifted to the secondary link?
67. BGP Graceful Restart, NSR and NSF?
68. How to use BGP as PE-CE backdoor link?
69. What is the advantage of using BGP AS Prepend?
70. What is cluster id in BGP?
71. What is the meaning of update-source loopback?
72. Can we use local preference outside the autonomous system?
73. What is confederation?
74. What is Route Reflector in BGP? Why is it required?
75. What will the BGP first check to see if a prefix is accessible?
76. What are the two methods for reducing the number of IBGP connection in a network?
77. What makes a neighbour internal BGP (iBGP)?
78. What the command “neighbour update-source” do?
79. Explain the term RIB in BGP?
80. Two BGP peers connected through a routed firewall are unable to establish a peering relationship. What could be the most likely cause?
81. What is the order of preference of attributes (route-map, filter-list,prefix-list, distribute-list ) when some or all are applied to one neighbour in BGP? Kindly share for inbound updates?
82. What is the order of preference of attributes (route-map, filter-list,prefix-list, distribute-list ) when some or all are applied to one neighbour in BGP? Kindly share for inbound updates?
83. How can I verify if a BGP router announces its BGP networks and propagates them?
84. What is the difference between always-compare-med and deterministic-med?
85. Does the route reflector change the next-hop attribute of a reflected prefix?
86. How can I announce a prefix conditionally to one ISP only when I lose the connection to my primary ISP?
87. How much of minimal RAM is required to learn complete BGP routing table from one BGP peer?
88. What are the benefits of configuring BGP peer groups?
89. What is the default BGP ConnectRetry timer
90. What does r RIB-Failure mean in the show ip bgp command output?
91. How can I filter all IP routes advertised to a BGP neighbour except the default route 0.0.0.0/0?
92. What is the version of BGP that first supported CIDR?
93. In the global routing table, can the same AS number shows up more than once in a path?
94. Can I run two BGP process on a single router?
95. What is the cost of external and internal BGP routes?
96. Which parameters and attributes have to be equal before MED is compared to select the best path?
97. How do we enable community propagation?
98. What is the purpose of route dampening?
99. In general which routes will affect by route dampening? eBGP or iBGP?
100. What is the default value of MED?