Home > ICND2 – EIGRP Questions 2

ICND2 – EIGRP Questions 2

October 12th, 2017 in ICND2 200-105 Go to comments

Question 1


When a router has no EIGRP feasible successor and the successor route to that destination network is in active status (the successor route is down, for example) a route recomputation occurs. A route recomputation commences with a router sending a query packet to all neighbors. Neighboring routers can either reply if they have feasible successors for the destination or optionally return a query indicating that they are performing a route recomputation. While in Active state, a router cannot change the next-hop neighbor it is using to forward packets. Once all replies are received for a given query, the destination can transition to Passive state and a new successor can be selected.

(Reference: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml#rout_states)

Question 2

Question 3


From the output we see a line “Gateway of last resort is to network”. Gateway of last resort refers to the next-hop router of a router’s current default route. Therefore all the traffic through this router to destination networks not matching any other networks or subnets in the routing table will be sent to (which is on Serial2) -> packet destined for (or an unknown destination) will be forwarded via Serial2.

An weird thing in the output above is the missing of the asterisk mask (*) which represents for the candidate default route. To set the “Gateway of last resort is to network” as the output above we can use these commands:

ip route
ip default-network

But these commands will create an static routing in the routing table with an asterisk mask. Maybe the output shown above is missing that route.

For more information about the command ip default-network please visit: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml.

Question 4


From the output of “show ip route” command on RouterB, we learn that RouterB does not learn any networks in RouterA. Also the “ is a summary, 00:00:03, Null0” line tells us this netwok is summarized.

Note: EIGRP performs auto-summarization each time it crosses a border between two major networks. For example, RouterA has networks of 172.16.x.x. It will perform auto-summarization when sending over network, which is in different major network ( and are called major networks in this case).

Question 5


All the above networks can be summarized to network but the question requires to “represent the LANs in Phoenix but no additional subnets” so we must summarized to network. The Phoenix router has 4 subnets so we need to “move left” 2 bits of “/24”-> /22 is the best choice -> D is correct.

Question 6


From the line “D [90/2195456] via, 00:03:31, Serial0/0″ we can see the IP address belongs to network and this network is between R1 and R3 -> Packet from network destined to a host on the LAN attached to router R1 will go directly from R3 to R1.

Question 7


From the routing table we learn that network is learned via 2 equal-cost paths ( & -> traffic to this network will be load-balancing.

Question 8

Question 10


Below is an example of the “show ip eigrp neighbors” command (from 9tut.com)


Question 11

Question 12


We notice that 3 routers are using different AS numbers so they do not become neighbors and cannot exchange their routing updates. We need to choose only one AS number and use it on all 3 routers to make them exchange routing updates.

In this case we don’t need to use the “no auto-summary” command because network is not separated by another major network.

Comments (7) Comments
  1. MikeJS
    April 1st, 2017

    Question 7 repeats the question in “EIGRP Questions”

  2. John
    April 2nd, 2017

    Sorry, Guys Where this questions

  3. domera
    June 26th, 2017

    can I please have the questions

  4. Zizo
    November 14th, 2017

    Question 6, the path is from R3 to R1 because of the lower AD than the R3 – R2 – R1 path

  5. Zizo
    November 14th, 2017

    er 14th, 2017
    Question 6, the path is from R3 to R1 because of the lower *FD than the R3 – R2 – R1 path

  6. Zizo
    November 14th, 2017

    On question 9, answer is C because: the AD of the is less than the FD of the

  7. Dank
    December 7th, 2017

    Can anyone explain question 9? Or feasible successors in general? Thanks