Soal-soal STP

1.      What are the possible trunking modes for a switch port? (choose three)

-          Transparent

-          Auto

-          On

-          Desirable

-          Client

-          Forwarding

Explanation :

Here, the trunk link is identified by its physical location as the switch module number and port
number. The trunking mode can be set to any of the following:
on-This setting places the port in permanent trunking mode. The corresponding switch
port at the other end of the trunk should be similarly configured because negotiation is not
allowed. The encapsulation or identification mode should also be manually configured.
off-This setting places the port in permanent non-trunking mode. The port will attempt
to convert the link to non-trunking mode.
desirable-Selecting this port will actively attempt to convert the link into trunking
mode. If the far end switch port is configured to on, desirable, or auto mode, trunking
will be successfully negotiated.

auto-The port will be willing to convert the link into trunking mode. If the far end switch
port is configured to on or desirable, trunking will be negotiated. By default, all Fast
Ethernet and Gigabit Ethernet links that are capable of negotiating using DTP are
configured to this mode. Because of the passive negotiation behavior, the link will never
become a trunk, if both ends of the link are left to the auto default.
nonegotiate-The port is placed in permanent trunking mode, but no DTP frames are
generated for negotiation. The far end switch port must be manually configured for
trunking mode.

2.      Which two of these statements regarding RSTP are correct? (choose two)

-          RSTP cannot operate with PVST+.

-          RSTP defines new port roles.

-          RSTP defines no new port states.

-          RSTP is a proprietary implementation of IEEE 802.1D STP.

-          RSTP is compatible with the original IEEE 802.1D STP.

3.     

Jawaban :

4.      Refer to the exhibit. Which statement is true?

-          The Fa0/11 role confirms that SwitchA is not the root bridge for VLAN 20

-          VLAN 20 is running the per VLAN spanning tree protocol.

-          The MAC address of the root bridge is 0017.596d.1580

-          SwitchA is not the root bridge, because not all of the interface roles are designated.

5.      In which circumstance are multiple copies of the same unicast frame likely to be transmitted in switched LAN?

-          After broken links are re-established

-          In an improperly implemented redundant topology

-          When upper-layer protocols require high reliability

-          During high traffic periods

-          When a dual ring topology is in use

Penjelasan :

If we connect two switches via 2 or more links and do not enable STP on these switches then a loop (which creates multiple copies of the same unicast frame) will occur. It is an example of an improperly implemented redundant topology.

6.      Refer to the exhibit. 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)

-          SwitchA, Fa0/2, designated

-          SwitchA, Fa0/1, root

-          SwitchB, Gi0/2, root

-          SwitchB, Gi0/1, designated

-          SwitchC, Fa0/2, root

-          SwitchD, Gi0/2, root

Penjelasan :

Lihat di sini pertanyaan no. 7

7.      Which three statements about RSTP are true? (choose three)

-          RSTP significantly reduces topology reconverging time after a link failure.

-          RSTP expends the STP port roles by adding the alternate and backup roles.

-          RSTP port states are blocking, discarding, learning, or forwarding.

-          RSTP also uses the STP proposal-agreement sequence.

-          RSTP use the same timer-based process as STP on point-to-point links.

-          RSTP provides a faster transition to the forwarding state on point-to-point links than STP does.

8.     

Jawaban :

9.      Refer to the exhibit. The output that is shown is generated at a switch. Which three of these statements are true? (Choose three)

-          All ports will be in a state of discarding, learning or forwarding.

-          Thirty VLANs have been configured on this switch.

-          The bridge priority is lower than the default value for spanning tree.

-          All interfaces that are shown are on shared media.

-          All designated ports are in a forwarding state.

-          The switch must be the root bridge for all VLANs on this switch.

Explanation :

From the output, we see that all ports are in Designated role (forwarding state) -> A and E are correct.

The command “show spanning-tree vlan 30″ only shows us information about VLAN 30. We don’t know how many VLAN exists in this switch -> B is not correct.

The bridge priority of this switch is 24606 which is lower than the default value bridge priority 32768 -> C is correct.

All three interfaces on this switch have the connection type “p2p”, which means Point-to-point environment – not a shared media -> D is not correct.

The only thing we can specify is this switch is the root bridge for VLAN 3o but we can not guarantee it is also the root bridge for other VLANs -> F is not correct.

10.  An administrator would like to configure a switch over a virtual terminal connection from location outside of the local LAN. Which of the following are required in order for the switch to be configured from a remote location?

-          The switch must be configured with an IP address, subnet mask, and default gateway.

-          The switch must be connected to a router over a VLAN trunk

-          The switch must be reachable through a port connected to its management VLAN

-          The switch console port must be connected to the Ethernet LAN

-          The switch management VLAN must be created and have a membership of at least one switch port

-          The witch must be fully configured as an SNMP agent.

11.  Computer 1 is consoles into switch A. Telnet connection and pings run from the command prompt on switch A fail. Which the following could cause this problem?

-          Switch A does not have a cdp entry for switch B or router JAX

-          Switch A does not have an IP address

-          Port 1 on Switch A should be an access port rather than a trunk port

-          Switch A is not directly connected to router JAX

-          Switch A does not have a default gateway assigned

Explanation :

IP address needs to be configured for ping test and to manage remotely via telnet on the switch..

Cukup dengan memasukkan ip address, telnet bisa jalan. Silahkan coba di lab.

12.  Refer to the exhibit. Given the output shown from this Cisco Catalyst 2950, what is the most likely reason that interface FastEthernet 0/10 is not the root port for VLAN 2?

Switch# show spanning-tree interface fastethernet0/10

-          This switch has more than one interface connected to the root network segment in VLAN 2.

-          This switch is running RSTP while the elected designated switch is running 802.1d Spanning Tree.

-          This switch interface has a higher path cost to the root bridge than another in the topology.

-          This switch has a lower bridge ID for VLAN 2 than the elected designated switch.

13.  Which cisco catalyst feature automatically disables the port in an operational portFast upon receipt of the BPDU?

-          BackboneFast

-          UplinkFast

-          RootGuard

-          BPDU Guard

-          BPDU Filter

14.  Refer to the exhibit. Which two statements are true of the interface on switch1? (choose two)

-          A hub is connected directly to FastEthernet0/5

-          FastEthernet0/1 is configured as a trunk link

-          FastEthernet0/5 has statically assigned mac address

-          Interface FastEthernet0/2 has been disable.

-          Multiple devices are connected directly to fastEthernet0/1

-          FastEthernet0/1 is connected to a host with multiple network interface card

15.  What value is primarily used to determine which port becomes the root port on each non-root switch in a spanning-tree topology?

-          lowest port MAC address

-          port priority number and MAC address.

-          VTP revision number

-          highest port priority number.

-          path cost

Explanation :

The path cost to the root bridge is the most important value to determine which port will become the root port on each non-root switch. In particular, the port with lowest cost to the root bridge will become root port (on non-root switch).

16.  Which two states are the port states when RSTP has converged? (choose two)

-          Blocking

-          learning

-          disabled

-          forwarding

-          listening

Explanation :

RSTP only has 3 port states that are discarding, learning and forwarding. When RSTP has converged there are only 2 port states left: discarding and forwarding but the answers don’t mention about discarding state so blocking state (answer A) may be considered the best alternative answer.

17.  Which three statements accurately describe layer 2 Ethernet switches?(choose three)

-           Microsegmentation decreases the number of collisions on the network.

-          if a switch receives a frame for an unkown destination,it uses ARP to resolve the address.

-          Spanning Tree Protocol allows switches to automatically share vlan information.

-          In a properly functioning network with redundant switched paths,each swiched aegment will contain one

-          root bridge with all its ports in the forwarding state.All other switches in that broadcast domain will have only one root port.

-          Establishing vlans increases the number of broadcast domains.

-          Switches that are configured with vlans make forwarding decisions based on both layer 2 and layer 3 address information.

18.  Which two of these are characteristics of the 802.1Q protocol? (Choose two)

-           It is a layer 2 messaging protocol which maintains vlan configurations across network.

-          It includes an 8-bit field which specifies the priority of a frame.

-          It is used exclusively for tagging vlan frames and dose not address network reconvergence following switched network topology changes.

-          It modifies the 802.3 frame header and thus requires that the FCS be recomputed.

-          It is a trunking protocol capable of earring untagged frames.

Explanation :

IEEE 802.1Q is the networking standard that supports Virtual LANs (VLANs) on an Ethernet network. It is a protocol that allows VLANs to communicate with one another using a router. 802.1Q trunks support tagged and untagged frames.

If a switch receives untagged frames on a trunk port, it believes that frame is a part of the native VLAN. Also, frames from a native VLAN are not tagged when exiting the switch via a trunk port.

The 802.1q frame format is same as 802.3. The only change is the addition of 4 bytes fields. That additional header includes a field with which to identify the VLAN number. Because inserting this header changes the frame, 802.1Q encapsulation forces a recalculation of the original FCS field in the Ethernet trailer.

Note: Frame Check Sequence (FCS) is a four-octet field used to verify that the frame was received without loss or error. FCS is based on the contents of the entire frame.

19.  A network administrator needs to configure port security on a switch.which two statements are true? (choose two)

-          The network administrator can apply port security to dynamic access ports

-          The network administrator can configure static secure or sticky secure mac addresses in the voice vlan.

-          The sticky learning feature allows the addition of dynamically learned addresses to the running configuration.

-          The network administrator can apply port security to EtherChannels.

-          When dynamic mac address learning is enabled on an interface,the switch can learn new addresses,up to the maximum defined.

20.  Refer to the exhibit. At the end of an RSTP election process, which access layer switch port will assume the discarding role?

-          Switch3, port fa0/1

-          Switch3, port fa0/12

-          Switch4, port fa0/11

-          Switch4, port fa0/2

-          Switch3, port Gi0/1

-          Switch3, port Gi0/2

Explanation:

Slection of the designated ports. The ports on the root brigde are designated ports. The designated port should be the one that has the lowest path cost to the root bridge. If the ports have the same path cost, the lowest ID switch port will be the designated port. If the switch ports have the same ID, the lowest number port will be the designated port

21.  Refer to the exhibit. This command is executed on 2960Switch:

2960Switch(config)# mac-address-table static 0000.00aa.aaaa vlan 10 interface fa0/1.

Which two of these statements correctly identify results of executing the command? (Choose two.)

-           Port security is implemented on the fa0/1 interface.

-          MAC address 0000.00aa.aaaa does not need to be learned by this switch.

-          Only MAC address 0000.00aa.aaaa can source frames on the fa0/1 segment.

-          Frames with a Layer 2 source address of 0000.00aa.aaaa will be forwarded out fa0/1.

-          MAC address 0000.00aa.aaaa will be listed in the MAC address table for interface fa0/1 only.

Explanation

The above command adds the MAC address 0000.00aa.aaaa to the MAC address table of the switch. This is called static MAC address. Static addresses have the following characteristics:

* Static addresses will not be removed from the address table when a given interface link is down.
* Static addresses are bound to the assigned interface and will not be moved. When a static address is seen on another interface, the address will be ignored and will not be written to the address table.
* A static address cannot be learned on another port until the address is removed with the no form of this command.

Static MAC address is not a Port Security feature -> A is not correct.

If the MAC address 0000.00aa.aaaa is seen again (on fa0/1 or other ports), it does not need to be learned because it already exists in the MAC address table of the switch -> B is correct.

Although configured with a static MAC address, switch can still learn other MAC addresses dynamically -> C is not correct.

Frames with a Layer 2 destination address (not source address) of 0000.00aa.aaaa will beforwarded out fa0/1 -> D is not correct.

22.  Which port state is introduced by Rapid-PVST?

-          Learning

-          Listening

-          Discarding

-          forwarding

Explanation

PVST+ is based on IEEE802.1D Spanning Tree Protocol (STP). But PVST+ has only 3 port states (discarding, learning and forwarding) while STP has 5 port states (blocking, listening, learning, forwarding and disabled). So discarding is a new port state in PVST+.

23.  Refer to the exhibit. Give this output for SwitchC, what should the network administrator’s next action be?

-          Check the trunk encapsulation mode for SwitchC’s fa0/1 port.

-          Check the duplex mode for SwitchC’s fa0/1 port.

-          Check the duplex mode for SwitchA’s fa0/2 port.

-          Check the trunk encapsulation mode for SwitchA’s fa0/2 port.