QUESTION NO: 22 Exhibit:

Based on the information shown above, what can be determined from the output shown?

A. The TestKing1 switch is using VTP.

B. This is the only switch in the LAN topology.

C. The TestKing1 switch is not the root switch.

D. The link to the root bridge is through a 1 Gbps connection.

E. Spanning Tree Protocol is disabled on the TestKing1 switch.

Answer: C Explanation:

The root ID of the switch is the default root ID assigned to all Cisco switches, in order to force this switch to become the Root switch you may issue the spanning-tree vlan 1 priority [0-61440 in increments of 4096] command.

QUESTION NO: 23

What is the purpose of the Spanning Tree Protocol (STP)?

A. To prevent routing loops B. To create a default route

C. To provide multiple gateways for hosts

D. To maintain a loop-free Layer 2 network topology E. To enhance the functions of SNMP

Answer: D Explanation:

STP's main task is to stop network loops from occurring on your Layer 2 network

(bridges or switches). It vigilantly monitors the network to find all links, making sure that no loops occur by shutting down any redundant ones. STP uses the spanning-tree

algorithm (STA) to first create a topology database, then search out and destroy redundant links. With STP running, frames will only be forwarded on the premium, STP-picked links.

QUESTION NO: 24

The TestKing network is shown below:

How will Spanning Tree affect the operation of the network devices shown in the graphic?

A. Spanning Tree will block client ports that suffer from excessive errors.

B. Spanning Tree will learn client MAC addresses and assign them to switch ports.

C. Spanning Tree will allow these switches to load balance across the redundant links to increase network throughput.

D. Spanning Tree will learn which of the redundant links should be blocked.

E. Spanning tree will automatically configure the switches with VLAN information.

Answer: D Explanation:

STP states are as follows:

Disabled-Ports that are administratively shut down by the network administrator, or by the system due to a fault condition, are in the Disabled state. This state is special and is not part of the normal STP progression for a port.

Blocking-After a port initializes, it begins in the Blocking state so that no bridging loops can form. In the Blocking state, a port cannot receive or transmit data and cannot add MAC addresses to its address table.

Instead, a port is allowed to receive only BPDUs so that the switch can hear from other neighboring switches. In addition, ports that are put into standby mode to remove a bridging loop enter the Blocking state.

Listening-The port will be moved from Blocking to Listening if the switch thinks that the port can be selected as a Root Port or Designated Port. In other words, the port is on its way to begin forwarding traffic.

In the Listening state, the port still cannot send or receive data frames. However, the port is allowed to receive and send BPDUs so that it can actively participate in the Spanning Tree topology process. Here, the port is finally allowed to become a Root Port or Designated Port because the switch can advertise the port by sending BPDUs to other switches. Should the port lose its Root Port or Designated Port status, it returns to the Blocking state.

Learning-After a period of time called the Forward Delay in the Listening state, the port is allowed to move into the Learning state. The port still sends and receives BPDUs as before. In addition, the switch can now learn new MAC addresses to add to its address table. This gives the port an extra period of silent participation and allows the switch to assemble at least some address table information.

Forwarding-After another Forward Delay period of time in the Learning state, the port is allowed to move into the Forwarding state. The port can now send and receive data frames, collect MAC addresses in its address table, and send and receive BPDUs. The port is now a fully functioning switch port within the Spanning Tree topology.

QUESTION NO: 25

Four TestKing switches are shown below:

Assuming these are the only four switches in the network and the switches are connected with redundant links, which switch will be elected as the spanning-tree root bridge?

A. TestKing1 B. TestKing2 C. TestKing3 D. TestKing4

Answer: A Explanation:

To elect the root bridge in the LAN, first check the priority value. The switch having lowest priority will win the race. If Priority Value is same then it checks the MAC Address, the switch having lowest MAC Address will be the root bridge. Here Switch 1 has the lowest MAC Address soit becomes the root bridge.

QUESTION NO: 26

Four TestKing switches are shown below:

The bridge ID for each switch and the bandwidth for each link is shown. Assuming that all switches are set to the default configuration, which ports will be blocking when Spanning Tree has converged? (Choose three.)

A. TestKingA port that connects to TestKingD B. TestKingA port that connects to TestKingB C. TestKingA port that connects to TestKingC D. TestKingB port that connects to TestKingC E. TestKingB port that connects to TestKingD F. TestKingD port that connects to TestKingA

Answer: A, B, E Explanation:

STP uses the concept of cost to determine many things. Selecting a Root Port involves evaluating the Root Path Cost. This value is the cumulative cost of all the links leading to the Root Bridge. A particular switch link has a cost associated with it, too, called the Path Cost. To understand the difference between these values, remember that only the Root Path Cost is carried inside the BPDU. As the Root Path Cost travels along, other switches can modify its value to make it cumulative. The Path Cost, however, is not contained in the BPDU. It is known only to the local switch where the port (or "path" to a neighboring switch) resides.

Path Costs are defined as a 1-byte value, with the default values shown in Table 9-3.

Generally, the higher the bandwidth of a link, the lower the cost of transporting data across it. The original IEEE 802.1D standard defined Path Cost as 1000 Mbps divided by the link bandwidth in Mbps. These values are shown in the center column of the table.

Modern networks commonly use Gigabit Ethernet and OC-48 ATM, which are both either too close to or greater than the maximum scale of 1000 Mbps. The IEEE now uses a nonlinear scale for Path Cost, as shown in the right column of the table.

All Remaining ports then root will be in blocking mode.

QUESTION NO: 27

Two TestKing switches are shown below:

This network is stable and operating properly. Assuming that default STP

configurations are running on both switches, which port will be in blocking mode?

A. Port Fa0/1 on TestKing1 B. Port Fa0/2 on TestKing1

C. Port Fa0/1 on TestKing2 D. Port Fa0/2 on TestKing2

Answer: A Explanation:

Spanning-Tree Protocol (STP) is a Layer 2 protocol that utilizes a special-purpose algorithm to discover physical loops in a network and effect a logical loop-free topology.

STP creates a loop-free tree structure consisting of leaves and branches that span the entire Layer 2 network. The actual mechanics of how bridges communicate and how the STP algorithm works will be discussed at length in the following topics. Note that the terms bridge and switch are used interchangeably when discussing STP. In addition, unless otherwise indicated, connections between switches are assumed to be trunks.

The switches move on to selecting Root Ports. The Root Port of a bridge is the port that is closest to the Root Bridge in terms of Path Cost. Every non-Root Bridge must select one Root Port. Again, bridges use the concept of cost to measure closeness. As with some routing metrics, the measure of closeness using STP is not necessarily reflected by hop count. Specifically, bridges track what is referred to as Root Path Cost, which is the cumulative cost of all links to the Root Bridge. So, Answer A is correct.

QUESTION NO: 28