1. | The Spanning Tree Protocol was created to overcome the problems of what type of bridging?
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2. | Bridge Protocol Data Units (BPDUs) are responsible for providing information for which four services in a spanning tree?
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3. | On what VLAN are Bridge Protocol Data Units (BPDUs) sent by default?
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4. | Which of the following provides a separate instance of Spanning Tree Protocol for every VLAN?
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5. | To configure a backup root bridge on a set-based switch, what command would be used?
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6. | How many Spanning Tree Protocol instances are supported on the 2950 switch?
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7. | Which of the following would change the VLAN port priority on an IOS-based switch to a value of 16?
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8. | When setting the VLAN port priority, what are the available values you can use?
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9. | When you’re using EtherChannel on your switches and a link failure occurs, what controlling device notifies the EARL of the failure?
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10. | From which of the following can PAgP form a bundle?
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11. | What does the STP use to choose a forwarding port if the port costs are equal on a switch?
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12. | What is used to make a point-to-point port enter almost immediately into forwarding state by decreasing the time of the listening and learning states?
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13. | What protocol sends Root Link Query BPDUs upon receiving an inferior BPDU?
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14. | Which of the following commands is used to create a bundle on a 4000 series switch?
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15. | Which of the following global configuration commands is used to turn on BackboneFast on an IOS-based switch?
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16. | Which of the following is true regarding PVST+? (Choose all that apply.)
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17. | What is the IEEE implementation of the STP?
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18. | How many spanning tree instances are defined with the PVST protocol running on a switch with six VLANs configured?
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19. | How many spanning tree instances are defined with the CST protocol running on a switch with six VLANs configured?
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20. | Which three of the following can STP use to determine the best path to the root bridge?
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Answers
1. | C The Spanning Tree Protocol was designed to help stop network loops that can happen with transparent bridge networks running redundant links. |
2. | A, B, C, E The Bridge Protocol Data Units are sent out every 2 seconds by default and provide information to switches throughout the internetwork. This includes finding redundant links, electing the root bridge, monitoring the links in the spanning tree, and notifying other switches in the network about link failures. |
3. | C VLAN 1 is a default VLAN and used for management by default. |
4. | D The Cisco proprietary protocol Per-VLAN Spanning Tree (PVST) uses a separate instance of spanning tree for each and every VLAN. |
5. | C The set spantree root secondary command enables you to configure a backup root bridge. |
6. | D The 2950 switch can support up to 1005 VLANs but only up to 64 STP instances. |
7. | A On an IOS-based switch, use the spanning-tree vlan vlan_number priority 16 from interface configuration to change the port priority. |
8. | A A priority from 0 to 63 can be set for each VLAN. |
9. | C Should one link in the bundle fail, the Ethernet Bundle Controller (EBC) informs the Enhanced Address Recognition Logic (EARL) ASIC of the failure, and the EARL in turn ages out all addresses learned on that link. |
10. | A PAgP bundled ports must all be configured the same, including the duplex and speed. Also, dynamic VLANs will not work, so VLANs must be assigned statically or must all be trunked ports. |
11. | A The switch uses the port ID to find the best forwarding port if the link costs are equal. |
12. | B PortFast is used to put a blocked port into forwarding state immediately upon a bootup of a point-to-point device such as a workstation or server. |
13. | D When BackboneFast is turned on, the Root Link Query BPDUs are sent out as soon as an inferior BPDU is received. This can enable faster convergence in the event of a backbone link failure. |
14. | B The command set port channel slot/port [on/off] is used to create an EtherChannel bundle. |
15. | B To enable BackboneFast on an IOS-based switch, use the spanning-tree backbonefast command, which turns the protocol on for every VLAN. |
16. | A, B, D PVST is proprietary to Cisco, and PVST+ is an extension of PVST. PVST+ enables non- PVST information to be accepted and received into PVST, adds configuration checking, and enables Cisco switches to support 802.1Q. |
17. | A The IEEE uses what is called Common Spanning Tree (CST), which is defined with IEEE 802.1Q. The IEEE 802.1Q defines one spanning tree instance for all VLANs. |
18. | C The PVST protocol defines one instance of STP per VLAN. |
19. | B The CST protocol defines one instance of STP per network regardless of the number of VLANs configured. |
20. | B, C, E The port cost, path cost, and port priority are used to determine the best path to the root bridge. |