Aug
23

I want to thank Rodney for this blog post idea. Rodney, like several others, did struggle a bit with some of the longer, scenario-based questions in the CCIE Written Exam. In fact, while these questions might not be too difficult, one tends to discover that time becomes a major factor in the written exam as a result of these question types.

In this blog post series, we will dissect some sample exam questions, and cover in detail how we might solve the query as quickly and efficiently as possible. Here is the first sample question:

Question 1 of 105

Examine the topology and partial router outputs shown in the Exhibits. How will the prefix of Loopback 0 on R1 appear on R6?

a) The prefix will be part of the External EIGRP learned route information

b) The prefix will be part of the Internal EIGRP learned route information

c) The prefix will be part of the eBGP learned route information

d) The prefix will be part of the iBGP learned route information

e) The prefix will not appear on R6

Exhibit 1

CCIE Written

Exhibit 2

hostname R1
!
interface Loopback0
ip address 1.1.1.1 255.255.255.0
!
interface FastEthernet0/0
ip address 10.10.10.1 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.60.60.1 255.255.255.0
duplex auto
speed auto
!
router eigrp 200
network 10.0.0.0
no auto-summary
!
router bgp 100
no synchronization
bgp log-neighbor-changes
network 1.1.1.0 mask 255.255.255.0
neighbor 10.10.10.2 remote-as 100
neighbor 10.60.60.6 remote-as 200
no auto-summary
!

Exhibit 3

hostname R2
!
interface FastEthernet0/0
ip address 10.10.10.2 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.20.20.2 255.255.255.0
duplex auto
speed auto
!
router eigrp 200
network 10.0.0.0
no auto-summary
!
router bgp 100
no synchronization
bgp log-neighbor-changes
neighbor 10.10.10.1 remote-as 100
no auto-summary
!

Exhibit 4

hostname R6
!
interface FastEthernet0/0
ip address 10.50.50.6 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.60.60.6 255.255.255.0
duplex auto
speed auto
!
router eigrp 200
redistribute bgp 200 metric 1000 0 255 1 1500
network 10.0.0.0
no auto-summary
!
router bgp 200
no synchronization
bgp log-neighbor-changes
neighbor 10.50.50.5 remote-as 200
neighbor 10.60.60.1 remote-as 100
no auto-summary

The first step in solving something like this is very simply not allowing yourself to become overwhelmed. Remember to break down a problem into smaller parts. Here is my mental logic as I begin...

"If R6 truly learns of the prefix from EIGRP, External EIGRP, eBGP, and iBGP, which protocol will win the Administrative Distance battle? eBGP certainly will win with its incredible AD of 20. So all I need to do is check the exhibits to ensure that R6 will learn of this prefix via eBGP!"

After going through this logic, I check the output of R1. Yes, it appears the prefix is properly advertised via BGP, and it should be sent to R6 via eBGP. I learn this from the neighbor statement, and the network statement on R1. I then check for the proper BGP config on R6. This just consists of the correct neighbor statement. Finally, I give the R2 config a quick peek, and immediately discover that it is not really relevant to answer this question.

I choose option "c) The prefix will be part of the eBGP learned route information" and move on to the next question with confidence. Notice that this may have looked really tough and complex, but it was actually quite simple and we only took about 2 minutes to answer it.

For more products to help with this Tier 1 knowledge, check out:

I sure hope you enjoyed the first post in this series, and as always, enjoy your studies immensely!

INE Instructor
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