TOP 100 OSPF INTERVIEW QUESTIONS
OSPF Interview Questions
Why are loopbacks advertised as /32 host routes in OSPF ?
How do I change the reference bandwidth in OSPF ?
How does OSPF calculate its metric or cost ?
What algorithm is used by OSPF if equal cost routes exist ?
Are OSPF routing protocol exchanges authenticated ?
What is the link-state retransmit interval, and what is the command to set it ?
Is it true that only the static option of the virtual link in OSPF allows discontiguous networks, regardless of the mask propagation properties ?
Does the Cisco OSPF support IP TOS-based routing?
Does the offset-list subcommand work for OSPF ?
Can an OSPF default be originated into the system based on external information on a router that does not itself have a default ?
Can I use the distribute-list in/out command with OSPF to filter routes ?
How can I give preference to OSPF inter-area routes over intra-area routes ?
When routes are redistributed between OSPF processes, are all shortest path first algorithm metrics preserved, or is the default metric value used ?
Which address-wild-mask pair should I use for assigning an unnumbered interface to an area ?
Can we have one numbered and other side unnumbered in OSPF ?
What is the reason for receiving “unknown routing protocol” error message when I configure “Router OSPF One” ?
What do the states DR, BDR, and DROTHER mean in show ip ospf interface command output ?
Why do I not see OSPF neighbors as FULL/DR or FULL/BDR on my serial link ?
Do I need any special commands to run OSPF over asynchronous links?
Which Cisco IOS Software release began support for per-interface authentication type in OSPF?
Can I control the P-bit when importing external routes into a not-so-stubby area (NSSA) ?
Why does OSPF show commands respond so slow ?
What does the clear ip ospf redistribution command do ?
How often does OSPF send out link-state advertisements (LSAs) ?
How do I stop individual interfaces from developing adjacencies in an OSPF network ?
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 ?
Why is it that my Cisco 800 router does not run OSPF ?
Should I use the same process number while configuring OSPF on multiple routers within the same network?
I have a router that runs Cisco Express Forwarding (CEF) and OSPF, who does load-balancing when there are multiple links to a destination?
How does OSPF use two Multilink paths to transfer packets ?
How can you detect the topological changes rapidly?
Does the 3825 Series Router support the OSPF Stub feature?
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?
Can we have OSPF run over a GRE tunnel ?
Is there a way to manipulate and prefer the Type 3 LSAs to originate from two different areas sent to the non-backbone area ?
What is the purpose of the “variable IP-OSPF-Transmit-Delay” ?
Is there a drop/flap of an OSPF neighborship when changing an OSPF area type from “nssa no-summary” to “nssa” ?
In the %OSPF-5-ADJCHG: Process ID, Nbr [ip address] on Port-channel31 from FULL to EXSTART, SeqNumberMismatch error message, what does SeqNumberMismatch signify ?
What is the maximum number of OSPF processes (VRF aware) on 7600/6500 platforms?
How does ISPF impact or improve the OSPF network?
Is there a way to compare Cisco NX-OS/IOS OSPF commands ?
Is there any feature of OSPF protocol for quick convergence and a slow re-convergence of routes ?
What are different neighbor states in OSPF ?
Give the command for defining the cost of a default route propagated into an area?
What is role of topology and routing table in OSPF ?
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 ?
Name types of LSA ?
Why do I receive the “cannot allocate router id” error message when I configure Router OSPF One ?
What are the different OSPF network types and give an example for each ?
What command would you use to create a totally stubby area?
Name tables which OSPF maintain ?
Which multicast addresses used in OSPF ?
On which router is the area default cost defined ?
With which network type will OSPF establish router adjacencies but not perform the DR/BDR election process?
What are the Route types in OSPF ?
What is the administrative distance of OSPF ?
What is the value of hello and Dead timers in OSPF ?
What are the Area Types ?
What are the different States in OSPF?
What must match before an adjacency ?
How to perform Inter-Area Summarization in OSPF ?
How to perform External Summarization ?
What are Virtual-Links ?
What is need of virtual Link ?
What is a Sham-Link ?
Explain the following syntax and what it will achieve: area 1 stub no-summary ?
What could be reason for OSPF neighbors being “stuck in 2 way” ?
What could be reason for OSPF neighbors being “stuck in Extart” ?
What could be reason for OSPF neighbors being “stuck in init” ?
What could be reason for OSPF neighbors being “stuck in loading” ?
What is the algorithm used by OSPF ?
What is OSPF Router ID and how is it elected ?
What is the DR/BDR in OSPF? How these are elected and in what scenario ?
What will happen if we make priority of a OSPF router as “zero” ?
Does DR/BDR election happen in OSPF Point to Point Network ?
What is Backbone area ?
What is stub area, Totally Stubby Area, Not So Stubby area (NSSA)?
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 ?
Explain the concept of Area Border Router (ABR) ?
Explain concept of Autonomous System Border Router (ASBR) ?
What is O E1, O E2 letters in OSPF? Which is default external type 1 or external type 2 ?
If any of the OSPF area is not stabilized, does it impact another area ?
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) ?
What is benefit of dividing network into areas ?
What parameters must match for 2 routers to become neighbors ?
What are various OSPF states?
Does OSPF form adjacencies with neighbors that are not on the same subnet ?
Explain OSPF LSA, LSU and LSR ?
What is difference between OSPF and EIGRP ?
What is difference between OSPF and IS-IS ?
Provide the 3 table types in OSPF ?
Is OSPF a classless or classfull protocol?
Which protocol does OSPF uses at the transport layer for communication ?
Can we use OSPF without backbone area?
Which RFC describes OSPF version 2 ?
By default OSPF will load balance over how many equal cost paths ?
OSPF is represented as protocol number _____ in the IP packet
Which are the 2 main functions of the DR ?
Which 2 parameters assist in DR election?
How to advertise a default-route if it doesn’t exist in the RIB?
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