New CCNA Troubleshooting Questions

By | July 20, 2017

 

This is an Updated CCNA Troubleshooting exam questions (2016). You might come across different IP addressing, Port allocation and Configurations.

As usual, take time and read through the question so as to clearly understand what Cisco want you to do.

Note: This network troubleshooting question are used for demonstration only,you might find a slight different IP addressing, Port allocation in the real CCNA exam. But it all works the same way if you could just grasp the technique.

I suggest you use packet tracer for practice.




Question 1

Refer to the exhibit.

 Based on the information given, which switch will be elected root bridge and why?
A. Switch A, because it has the lowest MAC address
B. Switch A, because it is the most centrally located switch
C. Switch B, because it has the highest MAC address
D. Switch C, because it is the most centrally located switch
E. Switch C, because it has the lowest priority
F. Switch D, because it has the highest priority

 Answer: E
 Explanation: 
To elect the root bridge in the LAN, firstly,  check the priority value. The switch having the lowest priority will win the election process. If Priority Value is the same then it checks the MAC Address; the switch having the lowest MAC Address will become the root bridge. In this case, switch C has the lowest MAC Address so it becomes the root bridge.

Read How Switches select root port and root bridge modes

Question 2
Refer to the exhibit. Complete this network diagram by dragging the correct device name or description to the correct location. Not all the names or descriptions will be used.

Answer:

Question 3

Refer to exhibit:


Which two destination addresses will be used by Host A to send data to Host C? (Choose two.)
A. the IP address of Switch 1
B. the MAC address of Switch 1
C. the IP address of Host C
D. the MAC address of Host C
E. the IP address of the router’s E0 interface
F. the MAC address of the router’s E0 interface
Answer: C,F
Explanation: 
Note: In the traffic of data through many different networks, the source and destination IP addresses are not changed. Only the source and destination MAC addresses are changed.

 In this case Host, A will use the IP address of Host C and the MAC address of E0 interface to send data. When the router receives this data, it replaces the source MAC address with its own E1 interfaces MAC address and replaces the destination MAC address with Host Cs MAC address before sending to Host C.




Question 4
Refer to the exhibit.


After HostA pings HostB, which entry will be in the ARP cache of HostA to support this transmission?

A. Exhibit A
B. Exhibit B
C. Exhibit C
D. Exhibit D
E. Exhibit E
F. Exhibit F
Answer: A
Explanation:
Since Host A is on a different network to host B , Host A pings will be sent to its default gateway 192.168.6.1. Host A sends a broadcast frame asking the MAC address of 192.168.6.1. This information (IP and MAC address of the default gateway) is saved in its ARP cache for later use.

Question 5
Refer to the exhibit.


Which three statements correctly describe Network Device A? (Choose three.)
A. With a network wide mask of 255.255.255.128, each interface does not require an IP address.
B. With a network wide mask of 255.255.255.128, each interface does require an IP address on a unique IP subnet.
C. With a network wide mask of 255.255.255.0, must be a Layer 2 device for the PCs to communicate with each other.
D. With a network wide mask of 255.255.255.0, must be a Layer 3 device for the PCs to communicate with each other.
E. With a network wide mask of 255.255.254.0, each interface does not require an IP address.
Answer : B,D,E
Explanation: 

If Subnet Mask is 255.255.255.128 the hosts vary from x.x.x.0 – x.x.x.127 & x.x.x.128- x.x.x.255, so the IP Addresses of 2 hosts fall in different subnets so each interface needs an IP an address so that they can communicate each other. If Subnet Mask is 255.255.255.0 the 2 specified hosts fall in different subnets so they need a Layer 3 device to communicate.
If Subnet Mask is 255.255.254.0 the 2 specified hosts are in the same subnet and network address belongs to the same Layer 2 domain and can communicate with each other directly using the Layer 2 address.

Question 6
Refer to the exhibit.


Host A pings interface S0/0 on router 3. What is the TTL value for that ping?
A. 252
B. 253
C. 254
D. 255
Answer: B
Explanation: 
Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it discards the packet marking it unreachable. This prevents packets from rotating forever. So before the router forwards a packet, the TTL still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL.

The picture below shows TTL values for each interface of each router and for Host B. Notice that Host A initializes ICMP packet with a TTL of 255:




Question 7
Refer to the exhibit.
A technician has installed SwitchB and needs to configure it for remote access from the CLI?


A. SwitchB(config)# interface FastEthernet 0/1

 SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0

SwitchB(config-if)# no shutdown

B. SwitchB(config)# interface vlan 1

    SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0

   SwitchB(config-if)# ip default-gateway 192.168.8.254 255.255.255.0

   SwitchB(config-if)# no shutdown

C. SwitchB(# iconfig)p default-gateway 192.168.8.254

    SwitchB(config)# interface vlan 1

   SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0

   SwitchB(config-if)# no shutdown

D. SwitchB(config)# ip default-network 192.168.8.254

   SwitchB(config)# interface vlan 1

  SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0

  SwitchB(config-if)# no shutdown

E. SwitchB(config)# ip route 192.168.8.254 255.255.255.0

    SwitchB(config)# interface FastEthernet 0/1

   SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0

   SwitchB(config-if)# no shutdown

Answer: C
Explanation: 
To remote access to SwitchB, The technician must configure a management IP address on a VLAN on that switch.VLAN 1 is often used as the management VLAN, which leaves it vulnerable.In the exhibit above, you can see that the Management Workstation is in a different subnet from the SwitchB. For internetwork communication to occur, you must configure at least one default gateway. This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.

VLAN 1 is often used as the management VLAN, which leaves it vulnerable.In the exhibit above, you can see that the Management Workstation is in a different subnet from the SwitchB. For internetwork communication to occur, you must configure at least one default gateway. This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.

This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.

Question 8
Refer to the exhibit.


Switch-1 needs to send data to a host with a MAC address of 00b0.d056.efa4. What will Switch-1 do with this data?
A. Switch-1 will drop the data because it does not have an entry for that MAC address.
B. Switch-1 will flood the data out all of its ports except the port from which the data originated.
C. Switch-1 will send an ARP request out all its ports except the port from which the data originated.
D. Switch-1 will forward the data to its default gateway.
Answer: B
Explanation: 
This question tests the operating principles of the Layer 2 switch. If the switch checks its MAC address table of Switch1 and cant find the MAC address of the host, The Switch1 will flood the data out all of its ports except the port from which the data originated to determine which port the host is located in. Then the host will now send back or responds back with its MAC address which is then stored in the Switch MAC address table.

Question 9
Refer to the exhibit.


A frame on VLAN 1 on switch S1 is sent to switch S2 where the frame is received on VLAN2. What causes this behavior?
A. trunk mode mismatches
B. allowing only VLAN 2 on the destination
C. native VLAN mismatches
D. VLANs that do not correspond to a unique IP subnet
Answer: C
Explanation:
Untagged Native VLANs. When frames are sent across a network from VLAN 1,  the switch assumed that the Native VLAN is VLAN 1 and VLAN 2. Now, the frame reaches S1 it is sent across the trunk link without any tags. In Summary, when the switch receives an untagged frame on a trunk link, it assumes that it is for the native VLAN and as a result forwards it to VLAN 2. So this particular behavior is due to a native VLAN mismatch

Now, the frame reaches S1 it is sent across the trunk link without any tags. In Summary, when the switch receives an untagged frame on a trunk link, it assumes that it is for the native VLAN and as a result forwards it to VLAN 2. So this particular behavior is due to a native VLAN mismatch

Question 10
Refer to the exhibit.


Which switch provides the spanning-tree designated port role for the network segment thatservices the printers?
A. Switch1
B. Switch2
C. Switch3
D. Switch4
Answer: C
Explanation:
Printers are connected by hubs. The spanning-tree designated port role is between Switch3 and Switch4. They have the same priority 32768. But when you look and compare their MAC addresses. Switch3 with a lower MAC address will provide a designated port for printers.