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350-501 · Question #599

Refer to the exhibit. Company A is running OSPF within its network, comprised of routers R2, R3, R4, and R5 and consisting of two areas. Company A just acquired Company B, which uses EIGRP on its…

The correct answer is B. Apply an inbound distribute list on R2 with a route map that permits only the necessary networks. To reduce the number of EIGRP routes received on ASBR R2 from R1, the network team must apply an inbound distribute list on R2, leveraging a route map to specifically permit only the necessary EIGRP networks.

Networking

Question

Refer to the exhibit. Company A is running OSPF within its network, comprised of routers R2, R3, R4, and R5 and consisting of two areas. Company A just acquired Company B, which uses EIGRP on its own R1. R1 has several routes in its routing table. The network engineering team at Company A otherwise operate independently. R2 will serve as the ASBR between the two networks. Which action must the team take to reduce the number of EIGRP routes received on R2 and include only the necessary routes in the routing table?

Exhibit

350-501 question #599 exhibit

Options

  • AApply an outbound distribute list on R3 and R4 to filter unnecessary intra-area routes from
  • BApply an inbound distribute list on R2 with a route map that permits only the necessary networks.
  • CImplement an offset list on R1 for the necessary networks.
  • DAttach an access list to the R2 interface connected to R1 that denies all traffic except for the

How the community answered

(52 responses)
  • A
    6% (3)
  • B
    83% (43)
  • C
    10% (5)
  • D
    2% (1)

Why each option

To reduce the number of EIGRP routes received on ASBR R2 from R1, the network team must apply an inbound distribute list on R2, leveraging a route map to specifically permit only the necessary EIGRP networks.

AApply an outbound distribute list on R3 and R4 to filter unnecessary intra-area routes from

Applying an outbound distribute list on R3 and R4 would filter OSPF routes within Company A's network, which does not address the requirement to filter EIGRP routes received from R1.

BApply an inbound distribute list on R2 with a route map that permits only the necessary networks.Correct

Applying an inbound distribute list on R2, specifically targeting routes received from R1's EIGRP domain, allows the ASBR to filter unwanted EIGRP routes before they are installed in R2's routing table or redistributed into OSPF. A route map linked to the distribute list provides granular control to permit only the necessary networks.

CImplement an offset list on R1 for the necessary networks.

An offset list modifies the metric of routes, influencing path selection, but it does not filter or prevent routes from being received or installed in the routing table.

DAttach an access list to the R2 interface connected to R1 that denies all traffic except for the

Attaching an access list to an interface to deny traffic filters data plane packets and has no effect on routing updates or the content of the routing table.

Concept tested: Route Filtering for Redistribution (Distribute List, Route Map)

Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_eigrp/configuration/15-mt/eigrp-15-mt-book/eigrp-dist-list.html

Topics

#Route Filtering#EIGRP#Distribute Lists#Route Maps

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