Home > ICND2 – Troubleshooting 2

ICND2 – Troubleshooting 2

October 4th, 2017 in ICND2 200-105 Go to comments

Question 1

Explanation

The “show ip nat statistics” only gives us information about NAT translation. We cannot know if IP routing is enabled or the VLANs are up not not.

The “show ip statistics” command does not exist.

With the “show ip interface brief” we can see if the interface VLANs are up or not but cannot see if IP routing is enabled or not. So let’s see what information can be learned with the “show ip route” command.

By using the command “show ip route” we will learn if IP routing is enabled. If it is not enabled we will see this output:

ip_routing_not_enabled.jpg

After enabling ip routing (via the “ip routing” in global configuration mode) we can see all the interfaces. For example:

ip_routing_enabled.jpg

If we shut down an interface VLAN (Vlan18)

Sw1(config)#interface vlan 18
Sw1(config-if)#shutdown

then we will not see it in the routing table any more.

ip_routing_enabled_shutdown_interface_vlan.jpg

Therefore if the statement “local VLANs are up” means “the interface VLANs are up” then the “show ip route” is the best answer in this case.

Note: The IOS used to test is IOSv15.1

Question 2

Explanation

To check the connectivity between a host and a destination (through some networks) we can use both “tracert” and “traceroute” commands. But the difference between these two commands is the “tracert” command can display a list of near-side router interfaces in the path between the source and the destination. The “traceroute” command has the same function of the “tracert” command but it is used on Cisco routers only, not on a PC -> B is correct.

Question 3

Explanation

Answer B is not correct because “debug access-list ” command does not exist.

The reason answer E is correct because this command can help us see if the access-list was applied to the correct interface or not.

In fact answer A does not help verify the access-list as the access-list can only filter traffic passing through the router (where the access-list is applied). It does not filter traffic that originates from the router itself.

Question 4

Explanation

The subnet of Fa0/0 of R2 is 172.16.109.0/26 (range from 172.16.109.0 to 172.16.109.63) which covers the subnet of S0/1 interface 172.16.109.4/30 so in fact the answer C is not correct. But from the output of the “show ip interface brief” command we see both Fa0/0 and S0/1 interfaces’ statuses are ‘up/up’ -> they are working normally. So we think there is a typo in the subnet mask of Fa0/0. It should not be ‘/26’ but longer one, ‘/28’, for example. So you should still choose answer C in this question.

Question 5

Explanation

From the output we see the Serial0/0 of RouterA is in “status up/protocol down” state which indicates a Layer 2 problem so the problem can be:

+ Keepalives mismatch
+ Encapsulation mismatch
+ Clocking problem

Question 6

Question 7

Question 8

Comments (3) Comments
  1. italiansdoitbetter
    November 2nd, 2017

    Hello, Q8. I knew that between a router and a host the cable to be used is the rollover, so that the answer should be D. What do you think?

  2. Whatever
    November 5th, 2017

    I think Q8 is a bit of a trick question. It cannot be D because the question states the host is connected to GigabitEthernet 0/0. For the answer to be D, the host would have to be connected to the console port. In my mind, this scenario would be for testing, because who takes a host (PC) and connects it directly to a router, except maybe for testing in a network closet. At any rate, technically, hooking a PC directly to a router requires a crossover cable, but also in modern networks with MDIX, straight through would probably work as well. It's a trick question.

  3. italiansdoitbetter
    November 6th, 2017

    That’s right! 🙂