| What characteristic of Ethernet makes a redundantly switched network prone to loops? | |
| Routers are only able to prevent loops at Layer 3, while Ethernet exists at Layer 2. | |
| The Ethernet protocol has no TTL mechanism. | |
| Switches lack the sophisticated software required to prevent loops. | |
| Looping of frames is a reliability mechanism built in to the Ethernet protocol. | |
| Refer to the exhibit. Server sends an ARP request for the MAC address of its default gateway. If STP is not enabled, what will be the result of this ARP request? | |
| Router_1 will kill the broadcast and reply with the MAC address of the next hop router. | |
| Switch_A will reply with the MAC address of the Router_1 E0 interface. | |
| Switch_A and Switch_B will continuously flood the message onto the network. | |
| Switch_B will broadcast the request and reply with the Router_1 address. | |
| The message will cycle around the network until its TTL is exceeded. | |
| What two elements will exist in a converged network with one spanning tree? (Choose two.) | |
| one root bridge per network | |
| all non-designated ports forwarding | |
| one root port per non-root bridge | |
| multiple designated ports per segment | |
| one designated port per network | |
| Which two criteria does a switch use to select the root bridge? (Choose two.) | |
| bridge priority | |
| switching speed | |
| number of ports | |
| base MAC address | |
| switch location | |
| memory size | |
| Which two ways is the information contained in BPDUs used by switches? (Choose two.) | |
| to prevent loops by sharing bridging tables between connected switches | |
| to set the duplex mode of a redundant link | |
| to determine the shortest path to the root bridge | |
| to determine which ports will forward frames as part of the spanning tree | |
| to activate looped paths throughout the network | |
| Which two statements describe the BIDs used in a spanning tree topology? (Choose two.) | |
| They are sent out by the root bridge only after the inferior BPDUs are sent. | |
| They consist of a bridge priority and MAC address. | |
| Only the root bridge will send out a BID. | |
| They are used by the switches in a spanning tree topology to elect the root bridge. | |
| The switch with the fastest processor will have the lowest BID. | |
| Refer to the exhibit. Spanning-tree port priorities are listed beneath each interface. The network administrator enters the spanning-tree vlan 1 root primary command on S4. What is the effect of the command? | |
| Port priority makes Gi0/2 on S1 a root port. | |
| S4 is already the root bridge, so there are no port changes. | |
| Spanning tree blocks Gi0/1 on S3 to prevent a redundant path from S1. | |
| S2 Gi0/1 becomes a non-designated port because Gi0/2 has a lower path cost to S4. | |
| S3 Gi0/2 transitions from designated port to root port because of path cost changes caused by the root change. | |
| In which STP state does a port record MAC addresses but not forward user data? | |
| blocking | |
| learning | |
| disabling | |
| listening | |
| forwarding | |
| What two features of the Spanning-Tree Protocol contribute to the time it takes for a switched network to converge after a topology change occurs? (Choose two.) | |
| the max-age timer | |
| the spanning-tree hold down timer | |
| the forward delay | |
| the spanning-tree path cost | |
| the blocking delay | |
| Which two items are true regarding the spanning-tree portfast command? (Choose two.) | |
| If the switch port is configured with PortFast, it waits 15 seconds before transitioning from a blocking to forwarding state. | |
| Enabling PortFast on trunks that connect to other switches improves convergence. | |
| If a switch port is configured with PortFast, it is an access port that immediately transitions from a blocking to forwarding state. | |
| Portfast enables the port to bypass the listening and learning states of STP. | |
| Portfast bypasses the learning state and moves immediately into blocking. | |
| What is the first step in the process of convergence in a spanning tree topology? | |
| | election of the root bridge |
| determination of the designated port for each segment | |
| blocking of the non-designated ports | |
| selection of the designated trunk port | |
| activation of the root port for each segment | |
| How can a network administrator influence which STP switch becomes the root bridge? | |
| Configure the switch as the static root bridge. | |
| Change the BPDU to a higher value than that of the other switches in the network. | |
| Change the BPDU to a lower value than that of the other switches in the network. | |
| Set the switch priority to a smaller value than that of the other switches in the network. | |
| Set the switch priority to a higher value than that of the other switches in the network. | |
| Which two statements correctly distinguish STP from RSTP? (Choose two.) | |
| After the spanning-tree algorithm is run, STP waits for the network to converge before placing ports into forwarding state. RSTP places alternate ports into forwarding state immediately. | |
| STP specifies backup ports. RSTP has only root ports, alternate ports, and designated ports. | |
| STP converges on a link-by-link basis. RSTP converges the entire spanning tree immediately. | |
| RSTP depends on switches to agree on port roles. STP assigns port roles unilaterally. | |
| Only in RSTP are the port state and port role tied together. | |
| Which two statements are correct concerning spanning tree? (Choose two.) | |
| Switches that are not running spanning tree still forward the BPDUs they receive. | |
| All switches in any one VLAN must run some form of spanning tree. | |
| PVST+ mode is the Cisco implementation of multiple spanning tree and is interchangeable with MST mode. | |
| Creating a VLAN also creates a spanning-tree instance for rapid PVST+. | |
| Rapid spanning tree converges on a link by link basis. | |
| For what purpose was the PVST+ protocol developed? | |
| to increase the size of BPDUs to improve performance between trunks | |
| to provide optimal root bridge placement in each VLAN | |
| to share STP information between common VLANs | |
| to reduce the amount of BPDUs running on the switch | |
| When PVST+ was developed, the Bridge ID was modified to include which information? | |
| protocol | |
| MAC address | |
| bridge priority | |
| VID | |
| Which three functions are performed by the BPDU for RSTP? (Choose three.) | |
| communicates current system state information every 30 seconds | |
| used as the link keepalive mechanism | |
| determines the designated port for each switch in the network | |
| tests for switching loops using a TTL mechanism | |
| topology change notification and acknowledgment | |
| proposal agreement process | |
| Which two actions does an RSTP edge port take if it receives a BPDU? (Choose two.) | |
| immediately loses its edge status | |
| inhibits the generation of a TCN | |
| goes immediately to a learning state | |
| disables itself | |
| becomes a normal spanning-tree port | |
| What three link types have been defined for Rapid Spanning-Tree Protocol? (Choose three.) | |
| shared | |
| end-to-end | |
| edge-type | |
| boundary-type | |
| point-to-many | |
| point-to-point | |
| Which three statements are accurate regarding RSTP and STP? (Choose three.) | |
| RSTP uses a faster algorithm to determine root ports. | |
| RSTP introduced the extended system ID to allow for more than 4096 VLANs. | |
| Both RSTP and STP use the portfast command to allow ports to immediately transition to forwarding state. | |
| Like STP PortFast, an RSTP edge port that receives a BPDU loses its edge port status immediately and becomes a normal spanning-tree port. | |
| Configuration commands to establish primary and secondary root bridges are identical for STP and RSTP. | |
| Because of the format of the BPDU packet, RSTP is backward compatible with STP. | |
| Refer to the exhibit. The network team is implementing STP as rapid PVST+. C1 must be the root bridge for all VLANs. What is the minimum combination of switches required to run an instance of spanning tree to guarantee loop-free performance? | |
| C1 | |
| C1, D1, and D2 | |
| D1 and D2 | |
| all switches | |
| C1 plus S2 or D1 or D2 | |
| Which two statements are true about the default operation of STP in a Layer 2 switched environment that has redundant connections between switches? (Choose two.) | |
| The root switch is the switch with the highest speed ports. | |
| Decisions on which port to block when two ports have equal cost depend on the port priority and identity. | |
| All trunking ports are designated and not blocked. | |
| Root switches have all ports set as root ports. | |
| Non-root switches each have only one root port. | |
| Refer to the exhibit. Which two statements are true about the active spanning-tree ports on switch SW4? (Choose two.) | |
| All ports listed with a role of “Desg” are connected to workstations or devices that do not participate in Spanning Tree Protocol. | |
| Based on default spanning-tree port costs, switch SW4 is directly connected to the root switch via a Fast Ethernet link. | |
| All interfaces are operating at 100 Mbps and transmitting BPDUs. | |
| Interface Fa0/16 is blocking to prevent a loop with interface Fa0/14. | |
| Interface Fa0/18 is connected to a downstream switch that has a higher spanning-tree cost to reach the root. | |
| Interface Fa0/16 is competing with interface Fa0/18 as the designated port for an upstream switch. | |
| Which two events occur when the hello time and max age parameters of the spanning-tree vlan 1 command are increased? (Choose two.) | |
| VLAN 1 has more BPDU traffic. | |
| VLAN 1 converges more quickly. | |
| The VLAN 1 network diameter increases. | |
| Switches running VLAN 1 reduce processor usage. | |
| VLAN 1 priority decreases. | |
| Refer to the exhibit. What can be determined from the output shown? | |
| Two hosts communicating between ports Fa0/2 and Fa0/4 have a cost of 38. | |
| The priority was statically configured to identify the root. | |
| STP is disabled on this switch. | |
| The timers have been altered to reduce convergence time. | |
