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Difficulty: MediumRouting Concepts and Dynamic Routing Protocols

A network administrator is evaluating dynamic routing protocol behaviors for a campus network infrastructure. Which of the following operational features specifically characterize Open Shortest Path First (OSPF) as a link-state routing protocol? (Select TWO.)

  1. It constructs a complete topological database of the network area by flooding Link-State Advertisements (LSAs).Answer
  2. It executes Dijkstra's Shortest Path First (SPF) algorithm to calculate the shortest path tree to destination networks.Answer
  3. C
    It encapsulates routing protocol updates directly into Layer 2 Ethernet frames to bypass Layer 3 routing lookup overhead.
  4. D
    It maps multiple private internal host IP addresses to a single external public IP address using transport-layer port translation.

Answer

The correct characteristics of OSPF as a link-state routing protocol are constructing a complete topological database via Link-State Advertisements (LSAs) and executing Dijkstra's Shortest Path First (SPF) algorithm to determine optimal paths.
The correct options accurately describe how link-state routing protocols function. OSPF routers flood Link-State Advertisements (LSAs) to build a synchronized topological map (LSDB) of the area, and each router independently runs Dijkstra's Shortest Path First (SPF) algorithm on this map to identify the shortest path to each destination network.

Step-by-Step Solution

1
Identify the fundamental mechanics of link-state routing protocols.
Link-state protocols require routers to advertise the state of their directly connected links to all routers within an area.
Flooding LSAs enables every router in the area to maintain an identical Link-State Database (LSDB).
2
Determine how link-state protocols compute optimal routes from the topology map.
Each router independently runs Dijkstra's SPF algorithm using the LSDB as the topology map.
This builds a shortest-path tree rooted at the local router to compute loop-free routes to every network prefix.
3
Evaluate and discard distractor statements that misattribute OSI layer operations or NAT mechanisms.
Discard the statements regarding Layer 2 frame encapsulation and IP address/port translation.
OSPF relies on IP Layer 3 encapsulation (protocol 89), and IP/port translation is an edge NAT feature rather than a dynamic routing mechanism.

Key Concept

Link-State Routing Protocol Mechanics (OSPF LSDB and SPF Algorithm)
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Topics

Routing Concepts and Dynamic Routing Protocols

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