OSPF Interview Questions

ANSWERS @ – https://ipwithease.com/product/ospf/

Get equipped with the best set of questions asked for OSPF :

1. Why are loopbacks advertised as /32 host routes in OSPF ?
2. How do I change the reference bandwidth in OSPF ?
3. How does OSPF calculate its metric or cost ?
4. What algorithm is used by OSPF if equal cost routes exist ?
5. Are OSPF routing protocol exchanges authenticated ?
6. What is the link-state retransmit interval, and what is the command to set it ?
7. Is it true that only the static option of the virtual link in OSPF allows discontiguous networks, regardless of the mask propagation properties ?
8. Does the Cisco OSPF support IP TOS-based routing?
9. Does the offset-list subcommand work for OSPF ?
10. Can an OSPF default be originated into the system based on external information on a router that does not itself have a default ?
11. Can I use the distribute-list in/out command with OSPF to filter routes ?
12. How can I give preference to OSPF inter-area routes over intra-area routes ?
13. When routes are redistributed between OSPF processes, are all shortest path first algorithm  metrics preserved, or is the default metric value used ?
14. Which address-wild-mask pair should I use for assigning an unnumbered interface to an area ?
15. Can we have one numbered and other side unnumbered in OSPF ?
16. What is the reason for receiving “unknown routing protocol” error message when I configure “Router OSPF One” ?
17. What do the states DR, BDR, and DROTHER mean in show ip ospf interface command output ?
18. Why do I not see OSPF neighbors as FULL/DR or FULL/BDR on my serial link ?
19. Do I need any special commands to run OSPF over asynchronous links?
20. Which Cisco IOS Software release began support for per-interface authentication type in OSPF?
21. Can I control the P-bit when importing external routes into a not-so-stubby area (NSSA) ?
22. Why does OSPF show commands respond so slow ?
23. What does the clear ip ospf redistribution command do ?
24. How often does OSPF send out link-state advertisements (LSAs) ?
25. How do I stop individual interfaces from developing adjacencies in an OSPF network ?
26. When I have two type 5 link-state advertisements (LSAs) for the same external network in the OSPF database, which path should be installed in the IP routing table ?
27. Why is it that my Cisco 800 router does not run OSPF ?
28. Should I use the same process number while configuring OSPF on multiple routers within the same network?
29. I have a router that runs Cisco Express Forwarding (CEF) and OSPF, who does load-balancing when there are multiple links to a destination?
30. How does OSPF use two Multilink paths to transfer packets ?
31. How can you detect the topological changes rapidly?
32. Does the 3825 Series Router support the OSPF Stub feature?
33. What does the error message %OSPF-4-FLOOD_WAR: Process process-id re-originates LSA ID ip address type-2 adv-rtr ip address in area area id means?
34. Can we have OSPF run over a GRE tunnel ?
35. Is there a way to manipulate and prefer the Type 3 LSAs to originate from two different areas sent to the non-backbone area ?
36. What is the purpose of the “variable IP-OSPF-Transmit-Delay” ?
37. Is there a drop/flap of an OSPF neighborship when changing an OSPF area type from “nssa no-summary” to “nssa” ?
38. In the %OSPF-5-ADJCHG: Process ID, Nbr [ip address] on Port-channel31 from FULL to EXSTART, SeqNumberMismatch error message, what does SeqNumberMismatch signify ?
39. What is the maximum number of OSPF processes (VRF aware) on 7600/6500 platforms?
40. How does ISPF impact or improve the OSPF network?
41. Is there a way to compare Cisco NX-OS/IOS OSPF commands ?
42. Is there any feature of OSPF protocol for quick convergence and a slow re-convergence of routes ?
43. What are different neighbor states in OSPF ?
44. Give the command for defining the cost of a default route propagated into an area?
45. What is role of topology and routing table in OSPF ?
46. When I issue the “show ip ospf neighbor” command, why do I only see FULL/DR and FULL/BDR, with all other neighbors showing 2-WAY/DROTHER ?
47. Name types of LSA ?
48. Why do I receive the “cannot allocate router id” error message when I configure Router OSPF One ?
49. What are the different OSPF network types and give an example for each ?
50. What command would you use to create a totally stubby area?
51. Name tables which OSPF maintain ?
52. Which multicast addresses used in OSPF ?
53. On which router is the area default cost defined ?
54. With which network type will OSPF establish router adjacencies but not perform the DR/BDR election process?
55. What are the Route types in OSPF ?
56. What is the administrative distance of OSPF ?
57. What is the value of hello and Dead timers in OSPF ?
58. What are the Area Types ?
59. What are the different States in OSPF?
60. What must match before an adjacency ?
61. How to perform Inter-Area Summarization in OSPF ?
62. How to perform External Summarization ?
63. What are Virtual-Links ?
64. What is need of virtual Link ?
65. What is a Sham-Link ?
66. Explain the following syntax and what it will achieve: area 1 stub no-summary ?
67. What could be reason for OSPF neighbors being “stuck in 2 way” ?
68. What could be reason for OSPF neighbors being “stuck in Extart” ?
69. What could be reason for OSPF neighbors being “stuck in init” ?
70. What could be reason for OSPF neighbors being “stuck in loading” ?
71. What is the algorithm used by OSPF ?
72. What is OSPF Router ID and how is it elected ?
73. What is the DR/BDR in OSPF? How these are elected and in what scenario ?
74. What will happen if we make priority of a OSPF router as “zero” ?
75. Does DR/BDR election happen in OSPF Point to Point Network  ?
76. What is Backbone area ?
77. What is stub area, Totally Stubby Area, Not So Stubby area (NSSA)?
78. Can area 1 and area 2 exchange or advertise networks if they are not connected to area 0 (Backbone area) ? What we need to do make it happen ?
79. Explain the concept of Area Border Router (ABR) ?
80. Explain concept of Autonomous System Border Router (ASBR) ?
81. What is O E1, O E2 letters in OSPF? Which is default external type 1 or external type 2 ?
82. If any of the OSPF area is not stabilized, does it impact another area ?
83. What is OSPF routes preference in order for the following list – External Type 2 (E2) , Intra-Area (O), External Type 1 (E1), NSSA Type 1 (N1), Inter-Area (O IA), NSSA Type 2 (N2) ?
84. What is benefit of dividing network into areas ?
85. What parameters must match for 2 routers to become neighbors ?
86. What are various OSPF states?
87. Does OSPF form adjacencies with neighbors that are not on the same subnet ?
88. Explain OSPF LSA, LSU and LSR ?
89. What is difference between OSPF and EIGRP ?
90. What is difference between OSPF and IS-IS ?
91. Provide the 3 table types in OSPF ?
92. Is OSPF a classless or classfull protocol?
93. Which protocol does OSPF uses at the transport layer for communication ?
94. Can we use OSPF without backbone area?
95. Which RFC describes OSPF version 2 ?
96. By default OSPF will load balance over how many equal cost paths ?
97. OSPF is represented as protocol number _____ in the IP packet
98. Which are the 2 main functions of the DR ?
99. Which 2 parameters assist in DR election?
100. How to advertise a default-route if it doesn’t exist in the RIB?

ANSWERS @ – https://ipwithease.com/product/ospf/

Order Answers of these OSPF Questions from above link!

Upon purchasing you will receive Answers of all above 100 OSPF Interview questions in easy to understand PDF Format explained with relevant Diagrams (where required) for better ease of understanding.

In case you are preparing to crack your next interview in the field of routing, then do check our DYNAMIC ROUTING COMBO ( BGP , EIGRP , OSPF , RIP , ROUTING )

ABOUT THE AUTHOR

Rashmi Bhardwaj

I am here to share my knowledge and experience in the field of networking with the goal being – “The more you share, the more you learn.”

I am a biotechnologist by qualification and a Network Enthusiast by interest. I developed interest in networking being in the company of a passionate Network Professional, my husband.

I am a strong believer of the fact that “learning is a constant process of discovering yourself.”
– Rashmi Bhardwaj (Author/Editor)