300-410 practice question 17 of 35

Which two statements about redistributing EIGRP into OSPF are true? (Choose two)

Full set: 636 questions

Domain Layer 3 Technologies

Answer options
A: The redistributed EIGRP routes appear as type 3 LSAs in the OSPF database
B: The redistributed EIGRP routes appear as type 5 LSAs in the OSPF database Correct answer
C: The administrative distance of the redistributed routes is 170
D: The redistributed EIGRP routes appear as OSPF external type 1
E: The redistributed EIGRP routes as placed into an OSPF area whose area ID matches the EIGRPautonomous system number
F: The redistributed EIGRP routes appear as OSPF external type 2 routes in the routing table Correct answer
Correct Answer:
B. The redistributed EIGRP routes appear as type 5 LSAs in the OSPF database; F. The redistributed EIGRP routes appear as OSPF external type 2 routes in the routing table
Explanation

When routes from an EIGRP autonomous system are redistributed into OSPF, the redistributing router becomes an Autonomous System Boundary Router (ASBR). The ASBR injects these external routes into the OSPF domain by generating Type 5 AS-External Link-State Advertisements (LSAs). By default, OSPF treats these redistributed routes as External Type 2 (E2). An E2 route's metric is the fixed redistribution cost and does not change as it propagates through the OSPF domain. The routing table entry for such a route is typically marked with "O E2".

Why Incorrect

A. Type 3 LSAs (Summary LSAs) are used by Area Border Routers (ABRs) to advertise routes from one area to another within the same OSPF autonomous system, not for external routes.
C. The administrative distance for all OSPF routes, including external ones, is 110 by default. The administrative distance of 170 applies to external EIGRP routes within an EIGRP domain.
D. While routes can be configured as External Type 1 (E1), the default behavior for redistribution into OSPF is to create External Type 2 (E2) routes.
E. There is no operational requirement or relationship that mandates an OSPF area ID must match the EIGRP autonomous system number for redistribution to occur.

References

1. Cisco Systems

Inc.

IP Routing: OSPF Configuration Guide

Cisco IOS Release 15M&T

"How to Configure OSPF" section

"Redistributing Routing Information" subsection.

This document states: "An autonomous system boundary router injects external routes into OSPF... External routes can be Type 1 (E1) or Type 2 (E2). The default is E2." It also clarifies that these external routes are advertised in Type 5 LSAs.

2. Cisco Systems

Inc.

Cisco IOS IP Routing: OSPF Command Reference

redistribute (OSPF) command.

The command syntax documentation shows that the metric-type argument for the redistribute command defaults to type 2. This confirms that without explicit configuration

redistributed routes become OSPF External Type 2.

3. Cisco Systems

Inc.

What Are Administrative Distances? Document ID: 26634.

This official document lists the default administrative distances for routing protocols. It specifies "OSPF" with a default distance of "110" and "External EIGRP" with a distance of "170". This confirms that once a route is in the OSPF domain

its AD is 110.

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