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Difficulty: MediumRouting Concepts and Dynamic Routing Protocols

A network administrator is deploying OSPF across an enterprise edge router connected to a service provider. The administrator configures a static default route (0.0.0.0/00.0.0.0/0) pointing toward the ISP gateway for external Internet destination handling. The internal routers within the enterprise network need to learn this default egress route automatically through the existing dynamic routing process without manually adding static routes to every downstream router. Which of the following configuration actions should the administrator perform on the edge router to fulfill this routing requirement?

  1. Issue the default-information originate command within the OSPF routing process configuration.Answer
  2. B
    Configure Port Address Translation (PAT) on the external interface connected to the ISP.
  3. C
    Change the default gateway interface encapsulation to assign incoming packets to Layer 2 frames.
  4. D
    Assign a High Availability Virtual IP (VIP) address to the edge router's WAN interface.

Answer

Issue the default-information originate command within the OSPF routing process configuration.
The correct action is to execute the default-information originate command under the OSPF router configuration mode. This command allows the autonomous system boundary router (ASBR) to inject the default route (0.0.0.0/00.0.0.0/0) into the OSPF domain, enabling all internal routers to dynamically learn the default path to external destinations.

Step-by-Step Solution

1
Identify the goal of distributing an existing static default route (0.0.0.0/00.0.0.0/0) to internal dynamic routing peers.
Recognize that OSPF requires an explicit instruction to originate and advertise default routing information into the LSA database.
By default, OSPF does not automatically redistribute static routes, including default routes, without specific protocol configuration.
2
Evaluate the correct protocol command used to inject a default path into OSPF.
Determine that default-information originate advertises 0.0.0.0/00.0.0.0/0 into OSPF.
This command generates a Type 5 LSA to inform all interior OSPF routers of the default gateway path.

Key Concept

Default Route Redistribution and Origination in Dynamic Routing Protocols
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Topics

Routing Concepts and Dynamic Routing Protocols

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