OSPF INTERVIEW QUESTIONS
Below are some of the important OSPF Interview Questions.
- What the Hello packet carries when we enable OSPF?
- What are the OSPF LSA types?
- What are area types? Why there are different area concepts?
- What is the main importance of the STUB network? Why it is been developed in OSPF?
- What will happen if we redistribute between different OSPF processes?
- How to generate the default route in OSPF?
- How external routes are advertised generally(E1 or E2)? How to change from E2 to E1?
- What is the LSA’s available in STUB and totally stub network?
- What is OSPF super Backbone area?
- What is the concept of auto-cost reference bandwidth in OSPF?
- Is there any DR and BDR concept in the /31 network?
- What are the different network types in OSPF?
- What are EXSTART and EXCHANGE states? Explain the difference with the help of information exchanged in each state.
- If Router-ID is the same between OSPF enabled routers will they form adjacency or not?
- What is LSA 7 and when it is being seen?
- How we can connect a normal area to a backbone area if they are not directly connected?
- Which LSAs are permitted in Totally NSSA?
- Which LSAs are permitted in Stub, Totally Stub, and NSSA?
- How will you generate a default route in an NSSA?
- Kindly explain the concept of Forward-address in OSPF LSA 5.
- What is forward-metric and when is it used on OSPF?
- In which state of OSPF, DR/BDR is elected?
- When does the OSPF router move from Idle to a Two-way state?
- What is Sham-link? How sham-link helps in preferring the provider-path as primary?
- Explain the loop-avoidance methods using down-bit and domain-tag in MPLS-VPN?
- What is the DNA bit in OSPF? Where is it seen in OSPF?
- In which of the OSPF states a peer stuck if we set the priority 0 on all routers in the shared network?
- How will you filter LSA5 in OSPF?
- Can we filter LSA1 in OSPF? Explain a few of the methods to filter LSA1.
- Which OSPF node generates LSA2 in OSPF?
- Which OSPF router generates LSA4 and what is the purpose of LSA4?
- What triggers an ABR to generate LSA4?
- Explain the difference between DBD messages sent Exstart and Exchange state.
- Explain the fields of an LSA header.
- Explain the use of "bgp redistribute-internal" command. Where is it configured?
- Explain the Attempt state in OSPF. When is it seen?
- Can two OSPF routers become neighbors if network-type is different on both ends?
- What are the criteria to make two OSPF routers neighbors have different network types?
- How can we set OSPF cost for a Gig or a 10 Gig Link?
- In which LSA do we find V|E|B flags. What are their meanings?
- Explain the difference b/w a STUB area and NSSA besides LSA5 and LSA7s?
- What is the difference between DBD and LSU Packets?
- What are Hello/Holdown timers of the OSPF NBMA network?
- How OSPF maintains reliability.
- What is the benefit of dividing the OSPF domain into multiple areas?
- Why do I receive the "cannot allocate router id" error message when I configure Router OSPF One?
- What Parameters Must Match For Two Routers To Become Neighbors?
- What is the difference between Adjacent routers and Neighbor routers in OSPF?
- How we can do route summarization in OSPF? Explain for both ABR and ASBR.
- Which multicast addresses are used by OSPF for communication?
- What is incremental OSPF?
- What is the purpose of the variable IP-OSPF-Transmit-Delay?
- Does the offset-list sub command work for OSPF?
- When
routes are redistributed between OSPF processes, are all shortest path
first algorithm (SPF) metrics preserved, or is the default metric value
used?
- Can we have OSPF run over a GRE tunnel?
- Explain the use of Virtual-Link in OSPF.
- Explain the ways you can filter some of the routes while redistributing any other IGP protocol into OSPF.
- Do iBGP routes get redistributed into OSPF by default?
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