Question
Topology
You are working as a network technician, study the exhibit carefully. Your boss has informed you that there have been problems with the WAN that is using EIGRP routing protocol. You are required to troubleshoot these problems.
Before going to the questions of this sim, we should have a quick review about GRE tunneling:
GRE Quick Summary
The picture below shows how to configure a GRE Tunnel between two routers, notice that the "tunnel destination" must be the IP address of the interface, not of the opposite tunnel.
Notice: The tunnel source on one router must be specified as the tunnel destination on the other router.
Below are the questions of this lab-sim.
Question 1
What is the reason for the ping between the HQ router and the 192.168.1.193 interface on the Branch2 router failing?
A - The default route is missing from the Branch2 router.
B - When running EIGRP over GRE tunnels, you must manually configure the neighbor address using the eigrp neighbor ip address command.
C - The tunnel numbers for the tunnel between the HQ router and the Branch2 router do not match.
D - The tunnel source is incorrect on the Branch2 router. It should be serial 2/0.
E - The AS number for the EIGRP process on Branch2 should be 1 and not 11.
Answer: E
Explanation:
First we should check the configuration of both HQ and Branch 2 routers by using the show running-config command
On HQ router:
On Branch2 router
From the outputs we learn that the AS numbers in two routers are not the same. They therefore do not become EIGRP neighbors and the ping between two routers should fail.
Question 2
For the following statements, what is preventing a successful ping between the HQ router and the 192.168.1.10 interface on the Branch3 router?
A - The default route is missing from the Branch3 router.
B - The tunnel interface numbers for the tunnel between the HQ router and the Branch3 router do not match.
C - The tunnel source is incorrect on the Branch3 router. It should be serial 2/0.
D - The IP address on the tunnel interface for the Branch3 router has wrong IP mask. It should be 255.255.255.252.
E - The network statement under router EIGRP on the Branch3 router is incorrect. It should be network 192.168.2.0.0.0.0.255.
Answer: A
Explanation:
The Branch3 router is missing the default route to HQ router's interface (Serial2/0) so the ping command will not work.
Question 3
What is preventing the HQ router and the Branch1 router from building up an EIGRP neighbor relationship?
A - When running EIGRP over GRE tunnels, you must manually configure the neighbor address using the eigrp neighbor ipaddress command.
B - The tunnel destination address is incorrect on the HQ router. It should be 10.2.1.1 to match the interface address of the Branch1 router.
C - The tunnel source is incorrect on the Branch1 router. It should be serial 2/0.
D - The default route is missing from the Branch1 router.
E - The tunnel interface numbers for the tunnel between the HQ router and Branch1 router do not match.
Answer: B
Explanation:
Use the show running-config command on HQ and Branch1 routers and we will see the tunnel destination address was wrongly configured on HQ router.
Question 4
What is the reason that tunnel 5 on the HQ router is down when its companion tunnel on the Branch5 router is up?
A - The IP address on the tunnel interface on Branch5 is incorrect. It should be 192.168.1.16 255.255.255.252.
B - The tunnel source for tunnel 5 is incorrect on the HQ router. It should be serial 2/0.
C - The tunnel numbers for tunnel between the HQ router and the Branch5 router do not match.
D - The tunnel destination address for tunnel 5 is incorrect on the HQ router. It should be 10.2.5.1 to match the interface address of the Branch5 router.
E - The tunnel interface for tunnel 5 on the HQ router is in the administrative down state.
Answer: B
Explanation:
Use the show running-config command on HQ router, we learn that the tunnel source configured on HQ is Serial1/0 but HQ router connects to the Internet via Serial2/0 interface -> the tunnel source configured on HQ router was incorrect.
Question 5
What is preventing the 192.168.1.150 network from appearing in the HQ router's routing table?
A - The default route is missing from the Branch4 router.
B - The IP address on the E0/0 interface for the Branch4 router has the wrong IP mask. It should be 255.255.255.252.
C - The network statement under router EIGRP on the Branch4 router is incorrect. It should be network 192.168.1.0 0.0.0.255.
D - When running EIGRP over GRE tunnels, you must manually configure the neighbor address using the eigrp neighbor ipaddress command.
E - The IP address on the tunnel interface on P4S-Branch4 is incorrect. It should be 192.168.1.12 255.255.255.252.
Answer: C
Explanation:
As you can guess, you will need to use the show running-config command on Branch4 router
From the show running-config output of Branch4, we learn that the EIGRP network was wrongly configured on this router. By configuring "network 192.168.1.14 0.0.0.0" the Branch4 will only advertise host 192.168.1.14 to HQ so HQ router will not know about the existence of 192.168.1.150 network.
Good resource:
http://www.cisco.com/en/US/tech/tk583/tk372/technologies_configuration_example09186a008009438e.shtml
