Nokia 4A0-113 OSPF study plan

Explain how the OSPF hello protocol establishes bidirectional reachability and list every field in the hello packet with its purpose

Diagram the OSPFv2 packet header and describe the role of each of the five packet types in adjacency formation and database synchronization

Compare point-to-point, broadcast, non-broadcast multi-access, point-to-multipoint, and point-to-multipoint non-broadcast network types by DR/BDR election behavior and default hello/dead timers

Build a table of the LSA types 1 through 5 and 7 mapping each to its originating router role, flooding scope, and the LSDB section it populates

Describe how the link-state database is synchronized using DBD, LSR, LSU, and LSAck exchanges and what each step guarantees

Construct a three-area topology on paper and label the Router-LSA links, network-LSA pseudonodes, and summary-LSAs that would appear in each area's database

Trace the SPF algorithm step by step on a six-router topology, showing the candidate list and shortest-path tree at each iteration

Distinguish intra-area, inter-area, external type 1, and external type 2 routes by their preference order and the cost calculation each uses

Explain how the ABR sets the cost of a type 3 summary LSA and how that cost is added to the intra-area cost at the receiving router

Identify which LSA types are flooded into a totally stubby area versus a normal area and justify each exclusion

Compare normal, stub, totally stubby, not-so-stubby, and totally not-so-stubby areas by permitted LSA types and default route injection behavior

Describe how type 7 LSAs are translated to type 5 at the NSSA ABR and explain the role of the P-bit and the translator election

Configure area range summarization on an ABR and explain when the summary is advertised and when it is suppressed

Explain how external route summarization works at an ASBR and why it applies only to redistributed routes

Predict the effect of summarization on a downstream router's LSDB size and SPF churn during a flapping prefix

List every parameter that must match for a hello to be accepted and explain the failure symptom for each mismatch

Describe the eight neighbor states and identify at which state each common failure mode stalls

Explain DR and BDR election, including the role of interface priority, the Router ID tiebreak, and why the election is non-preemptive

Configure OSPF over a point-to-multipoint non-broadcast network type and explain why it avoids the need for a full mesh

Describe how NBMA environments are handled with neighbor statements versus point-to-multipoint conversion and the tradeoffs of each

Configure a single-area OSPF instance on Nokia SR OS, including router ID, area, interface, and passive settings, and verify with the appropriate show commands

Configure a multi-area topology with an ABR, an ASBR performing route redistribution, and area summarization

Apply and verify OSPF authentication on SR OS interfaces and explain the difference between simple password and MD5 authentication

Use SR OS show and debug commands to inspect the LSDB, neighbor table, and SPF log, and interpret their output

Configure OSPF metrics, reference bandwidth, and export policies that control which routes are redistributed

Configure MD5 and SHA-based authentication on SR OS and describe how the key ID and key chain are matched between neighbors

Explain virtual links: when they are required, how the transit area is used, and what configuration each endpoint needs

Describe how OSPF handles MTU mismatch, and explain why an MTU mismatch causes a neighbor to stall in ExStart

Configure graceful restart or helper behavior and explain what state is preserved during a control-plane restart

Identify the security risks of unauthenticated OSPF and describe how authentication and passive interfaces mitigate them

Design a multi-area topology that keeps each area under a reasonable router count and justify the area boundaries chosen

Explain the impact of LSA flooding and SPF runs on router CPU during a large-scale topology change and describe how area design limits that impact

Compare the scaling effects of stub areas, summarization, and route filtering on LSDB size and SPF frequency

Describe the OSPFv3 differences relevant to scaling, including per-link LSA handling and the use of link-local addresses

Analyze a scenario where an ABR is also an ASBR and explain the route preference implications

Complete a timed full-length practice set and score each domain separately to identify remaining weak areas

Re-derive from memory the LSA type table, area type matrix, and SPF steps without notes

Reconfigure the week 5 topology from a blank SR OS configuration within 30 minutes

Review every missed practice question and write the underlying concept in one sentence each

Summarize the five most commonly tested OSPF behaviors in your own words