What information about the interfaces on the Main_Campus router is true?

Refer to the exhibit.

image097 - 
What information about the interfaces on the Main_Campus router is true?
What information about the interfaces on the Main_Campus router is true?
A. The LAN interfaces are configured on different subnets.
B. Interface FastEthernet 0/0 is configured as a trunk.
C. The Layer 2 protocol of interface Serial 0/1 is NOT operational.
D. The router is a modular router with five FastEthernet interfaces.
E. Interface FastEthernet 0/0 is administratively deactivated.

Answer: B
Explanation:
Interface fa0/0 breaks into sub-interfaces and Main_Campus router is connected with switch via fa0/0 .Subinterfaces configured with different subnet masks so the same switch has multiple vlans and allows communication between these VLAN’s. For routing and inter-vlan we need to configure a trunk port. So B will be the correct answer.

What address is a feasible successor?

Refer to the exhibit.

image151 - 
What address is a feasible successor?
What address is a feasible successor?
A. 172.16.4.0
B. 10.1.4.4
C. 10.1.2.2
D. 172.16.3.0

Answer: C
Explanation:
The feasible condition states:
“To qualify as a feasible successor, a router must have an AD less than the FD of the current successor route”.
In this case, we see 10.1.2.2 shows an AD less than the current successor of 10.1.4.4

Which switch provides the spanning-tree designated port role for the network segment that services the printers?

Refer to the exhibit

image063 - 
Which switch provides the spanning-tree designated port role for the network segment that services the printers?
Which switch provides the spanning-tree designated port role for the network segment that services the printers?
A. Switch1
B. Switch2
C. Switch3
D. Switch4

Answer: C
Explanation:
First, the question asks what switch services the printers, so it can be Switch 3 or Switch 4 which is connected directly to the Printers.
Designated port is a port that is in the forwarding state. All ports of the root bridge are designated ports.
Switch 3 and Switch 4 has same priority so it will see on lowest MAC address and here switch 3 has lowest MAC address. So switch 3 segment will play a Designated port role.
By comparing the MAC address of Switch 3 and Switch 4 we found that the MAC of Switch 3 is smaller. Therefore the interface connected to the Printers of Switch 3 will become designated interface and the interface of Switch 4 will be blocked.

Which protocol supports sharing the VLAN configuration between two or more switches?

Which protocol supports sharing the VLAN configuration between two or more switches?
A. multicast
B. STP
C. VTP
D. split-horizon

Answer: C
Explanation:
“VTP allows a network manager to configure a switch so that it will propagate VLAN configurations to other switches in the network”
VTP minimizes misconfigurations and configuration inconsistencies that can cause problems, such as duplicate VLAN names or incorrect VLAN-type specifications. VTP helps you simplify management of the VLAN database across multiple switches.
VTP is a Cisco-proprietary protocol and is available on most of the Cisco switches.

Which parameter would you tune to affect the selection of a static route as a backup, when a dynamic protocol is also being used?

Which parameter would you tune to affect the selection of a static route as a backup, when a dynamic protocol is also being used?
A. hop count
B. administrative distance
C. link bandwidth
D. link delay
E. link cost

Answer: B
Explanation:
What Is Administrative Distance?
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094195.shtml
Administrative distance is the feature that routers use in order to select the best path. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value. Lowest Administrative distance will be chosen first.

image111 - Which parameter would you tune to affect the selection of a static route as a backup, when a dynamic protocol is also being used?

Which two statements about the OSPF Router ID are true? (Choose two.)

Which two statements about the OSPF Router ID are true? (Choose two.)
A. It identifies the source of a Type 1 LSA.
B. It should be the same on all routers in an OSPF routing instance.
C. By default, the lowest IP address on the router becomes the OSPF Router ID.
D. The router automatically chooses the IP address of a loopback as the OSPF Router ID.
E. It is created using the MAC Address of the loopback interface.

Answer: A, D
Explanation:
From the output of the “show ip ospf database”:
r120#show ip ospf data
OSPF Router with ID (10.0.0.120) (Process ID 1)
Next, who are the other routers in our area?
Router Link States (Area 1)
Link ID         ADV Router      Age         Seq#       Checksum Link count

Which statement about DTP is true?

Which statement about DTP is true?
A. It uses the native VLAN.
B. It negotiates a trunk link after VTP has been configured.
C. It uses desirable mode by default.
D. It sends data on VLAN 1.

Answer: A
Explanation:
Disabling Dynamic Trunking Protocol (DTP)
Cisco’s Dynamic Trunking Protocol can facilitate the automatic creation of trunks between two switches. When two connected ports are configured in dynamic mode, and at least one of the ports is configured as desirable, the two switches will negotiate the formation of a trunk across the link. DTP isn’t to be confused with VLAN Trunking Protocol (VTP), although the VTP domain does come into play.

image057 - Which statement about DTP is true?
DTP on the wire is pretty simple, essentially only advertising the VTP domain, the status of the interface, and it’s DTP type. These packets are transmitted in the native (or access) VLAN every 60 seconds both natively and with ISL encapsulation (tagged as VLAN 1) when DTP is enabled.

At the end of an RSTP election process, which access layer switch port will assume the discarding role?

Refer to the exhibit.

image065 - 
At the end of an RSTP election process, which access layer switch port will assume the discarding role?
At the end of an RSTP election process, which access layer switch port will assume the discarding role?
A. Switch3, port fa0/1
B. Switch3, port fa0/12
C. Switch4, port fa0/11
D. Switch4, port fa0/2
E. Switch3, port Gi0/1
F. Switch3, port Gi0/2

Answer: C
Explanation:
In this question, we only care about the Access Layer switches (Switch3 & 4). Switch 3 has a lower bridge ID than Switch 4 (because the MAC of Switch3 is smaller than that of Switch4) so both ports of Switch3 will be in forwarding state. The alternative port will surely belong to Switch4.
Switch4 will need to block one of its ports to avoid a bridging loop between the two switches. But how does Switch4 select its blocked port? Well, the answer is based on the BPDUs it receives from Switch3. A BPDU is superior than another if it has:

Which three of these show the correct RSTP port roles for the indicated switches and interfaces?

Refer to the exhibit.

image069 - 
Which three of these show the correct RSTP port roles for the indicated switches and interfaces?
Each of these four switches has been configured with a hostname, as well as being configured to run RSTP. No other configuration changes have been made.
Which three of these show the correct RSTP port roles for the indicated switches and interfaces? (Choose three.)
A. SwitchA, Fa0/2, designated
B. SwitchA, Fa0/1, root
C. SwitchB, Gi0/2, root
D. SwitchB, Gi0/1, designated
E. SwitchC, Fa0/2, root
F. SwitchD, Gi0/2, root

Answer: A, B, F
Explanation:
The question says "no other configuration changes have been made" so we can understand these switches have the same bridge priority. SwitchC has lowest MAC address so, it will become root bridge and 2 of its ports (Fa0/1 & Fa0/2) will be designated ports (DP). Because SwitchC is the root bridge the 2 ports nearest SwitchC on SwitchA (Fa0/1) and SwitchD (Gi0/2) will be root ports (RP) -> B and F are correct.
SwitchB must have a root port so which port will it choose? To answer this question we need to know about STP cost and port cost.
In general, "cost" is calculated based on bandwidth of the link. The higher the bandwidth on a link, the lower the value of its cost. Below are the cost values you should memorize:
Link speed Cost SwitchB will choose the interface with lower cost to the root bridge as the root port so we must calculate the cost on interface Gi0/1 & Gi0/2 of SwitchB to the root bridge. This can be calculated from the "cost to the root bridge" of each switch because a switch always advertises its cost to the root bridge in its BPDU. The receiving switch will add its local port cost value to the cost in the BPDU.
SwitchC advertises its cost to the root bridge with a value of 0. Switch D adds 4 (the cost value of 1Gbps link) and advertises this value (4) to SwitchB. SwitchB adds another 4 and learns that it can reach SwitchC via Gi0/1 port with a total cost of 8. The same process happens for SwitchA and SwitchB learns that it can reach SwitchC via Gi0/2 with a total cost of 23 -> Switch B chooses Gi0/1 as its root port.
Now our last task is to identify the port roles of the ports between SwitchA & SwitchB. It is rather easy as the MAC address of SwitchA is lower than that of SwitchB so Fa0/2 of SwitchA will be designated port while Gi0/2 of SwitchB will be alternative port.