more 1-4 Flashcards
Which impact does adding a Layer 2 switch have on a network?
an increase in the number of dropped frames
an increase in the size of the broadcast domain
an increase in the number of network collisions
an increase in the size of the collision domain
an increase in the size of the broadcast domain
Explanation: Adding a Layer 2 switch to a network increases the number of collision domains and increases the size of the broadcast domain. Layer 2 switches do not decrease the amount of broadcast traffic, do not increase the amount of network collisions and do not increase the number of dropped frames.
Which characteristic describes cut-through switching?
Error-free fragments are forwarded, so switching occurs with lower latency.
Frames are forwarded without any error checking.
Only outgoing frames are checked for errors.
Buffering is used to support different Ethernet speeds.
Frames are forwarded without any error checking.
Explanation: Cut-through switching reduces latency by forwarding frames as soon as the destination MAC address and the corresponding switch port are read from the MAC address table. This switching method does not perform any error checking and does not use buffers to support different Ethernet speeds. Error checking and buffers are characteristics of store-and-forward switching.
What is the significant difference between a hub and a Layer 2 LAN switch?
A hub extends a collision domain, and a switch divides collision domains.
A hub divides collision domains, and a switch divides broadcast domains.
Each port of a hub is a collision domain, and each port of a switch is a broadcast domain.
A hub forwards frames, and a switch forwards only packets.
A hub extends a collision domain, and a switch divides collision domains.
Explanation: Hubs operate only at the physical layer, forwarding bits as wire signals out all ports, and extend the collision domain of a network. Switches forward frames at the data link layer and each switch port is a separate collision domain which creates more, but smaller, collision domains. Switches do not manage broadcast domains because broadcast frames are always forwarded out all active ports.
Which statement is correct about Ethernet switch frame forwarding decisions?
Frame forwarding decisions are based on MAC address and port mappings in the CAM table.
Cut-through frame forwarding ensures that invalid frames are always dropped.
Only frames with a broadcast destination address are forwarded out all active switch ports.
Unicast frames are always forwarded regardless of the destination MAC address.
Frame forwarding decisions are based on MAC address and port mappings in the CAM table.
Explanation: Cut-through frame forwarding reads up to only the first 22 bytes of a frame, which excludes the frame check sequence and thus invalid frames may be forwarded. In addition to broadcast frames, frames with a destination MAC address that is not in the CAM are also flooded out all active ports. Unicast frames are not always forwarded. Received frames with a destination MAC address that is associated with the switch port on which it is received are not forwarded because the destination exists on the network segment connected to that port.
How do switch buffers affect network performance?
They provide error checking on the data received.
They store frames received, thus preventing premature frame discarding when network congestion occurs.
They provide extra memory for a particular port if autonegotiation of speed or duplex fails.
They hold data temporarily when a collision occurs until normal data transmission resumes.
They store frames received, thus preventing premature frame discarding when network congestion occurs.
Explanation: Switches have large frame buffers that allow data waiting to be transmitted to be stored so the data will not be dropped. This feature is beneficial especially if the incoming traffic is from a faster port than the egress port used for transmitting.
Which switch characteristic helps keep traffic local and alleviates network congestion?
high port density
fast port speed
large frame buffers
fast internal switching
high port density
Explanation: Switches that have a lot of ports (high port density) reduce the number of switches required and keep some of the traffic locally on the switch, thus removing the need to send it between switches.
Which switch component reduces the amount of packet handling time inside the switch?
ASIC
Explanation: Application-specific integrated circuits (ASICs) are used in Cisco switches to speed up switch operations so that the switch can have an increased number of ports without degrading switch performance.
The first step a switch does when processing a frame is to see if the source MAC address is in the MAC address table. If the address is not there, the switch adds it. The switch then examines the destination MAC address and compares it to the MAC address table. If the address is in the table, the switch forwards the frame out the corresponding port. If the address is missing from the table, the switch will forward the frame to all ports except the port through which the frame arrived.
the answer is the question
What information is added to the switch table from incoming frames?
source MAC address and incoming port number
destination MAC address and incoming port number
source IP address and incoming port number
destination IP address and incoming port number
source MAC address and incoming port number
Explanation: A switch “learns” or builds the MAC address table based on the source MAC address as a frame comes into the switch. A switch forwards the frame onward based on the destination MAC address.
Which switching method ensures that the incoming frame is error-free before forwarding?
cut-through
FCS
fragment free
store-and-forward
store-and-forward
Explanation: Two methods used by switches to transmit frames are store-and-forward and cut-through switching. The store-and-forward method performs error checking on the frame using the frame check sequence (FCS) value before sending the frame. In contrast, cut-through switching sends the frame as soon as the destination MAC address part of the header has been read and processed.
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How many broadcast domains are displayed?
1 4 8 16 55
8
Explanation: A router defines a broadcast boundary, so every link between two routers is a broadcast domain. In the exhibit, 4 links between routers make 4 broadcast domains. Also, each LAN that is connected to a router is a broadcast domain. The 4 LANs in the exhibit result in 4 more broadcast domains, so there are 8 broadcast domains in all.
Under which two occasions should an administrator disable DTP while managing a local area network? (Choose two.)
when connecting a Cisco switch to a non-Cisco switch
when a neighbor switch uses a DTP mode of dynamic auto
when a neighbor switch uses a DTP mode of dynamic desirable
on links that should not be trunking
on links that should dynamically attempt trunking
on links that should not be trunking
when connecting a Cisco switch to a non-Cisco switch
Explanation: Cisco best practice recommends disabling DTP on links where trunking is not intended and when a Cisco switch is connected to a non-Cisco switch. DTP is required for dynamic trunk negotiation.
Which two characteristics describe the native VLAN? (Choose two.)
Designed to carry traffic that is generated by users, this type of VLAN is also known as the default VLAN.
The native VLAN traffic will be untagged across the trunk link.
This VLAN is necessary for remote management of a switch.
High priority traffic, such as voice traffic, uses the native VLAN.
The native VLAN provides a common identifier to both ends of a trunk.
The native VLAN traffic will be untagged across the trunk link.
The native VLAN provides a common identifier to both ends of a trunk.
Explanation: The native VLAN is assigned to 802.1Q trunks to provide a common identifier to both ends of the trunk link. Whatever VLAN native number is assigned to a port, or if the port is the default VLAN of 1, the port does not tag any frame in that VLAN as the traffic travels across the trunk. At the other end of the link, the receiving device that sees no tag knows the specific VLAN number because the receiving device must have the exact native VLAN number. The native VLAN should be an unused VLAN that is distinct from VLAN1, the default VLAN, as well as other VLANs. Data VLANs, also known as user VLANs, are configured to carry user-generated traffic, with the exception of high priority traffic, such as VoIP. Voice VLANs are configured for VoIP traffic. The management VLAN is configured to provide access to the management capabilities of a switch.
On a switch that is configured with multiple VLANs, which command will remove only VLAN 100 from the switch?
Switch# delete flash:vlan.dat
Switch(config-if)# no switchport access vlan 100
Switch(config-if)# no switchport trunk allowed vlan 100
Switch(config)# no vlan 100
Switch(config)# no vlan 100
Explanation: To remove all VLANs from a switch, the delete flash:vlan.dat command would be used. To change the assigned VLAN for an interface, the no switchport access vlan 100 interface configuration command would be used. To remove VLAN 100 as an allowed VLAN on a trunk, the no switchport trunk allowed vlan 100 would be used, but this would not remove the VLAN from the switch. To delete a single VLAN, such as VLAN 100, the no vlan 100 global configuration command would be used.
Refer to the exhibit. A network administrator is reviewing port and VLAN assignments on switch S2 and notices that interfaces Gi0/1 and Gi0/2 are not included in the output. Why would the interfaces be missing from the output?
https://itexamanswers.net/wp-content/uploads/2019/12/CCNA-2-v7-Modules-1-4-Switching-Concepts-VLANs-and-InterVLAN-Routing-Exam-27.jpg
There is a native VLAN mismatch between the switches.
There is no media connected to the interfaces.
They are administratively shut down.
They are configured as trunk interfaces.
They are configured as trunk interfaces.
Explanation: Interfaces that are configured as trunks do not belong to a VLAN and therefore will not show in the output of the show vlan brief commands.
A network contains multiple VLANs spanning multiple switches. What happens when a device in VLAN 20 sends a broadcast Ethernet frame?
All devices in all VLANs see the frame.
Devices in VLAN 20 and the management VLAN see the frame.
Only devices in VLAN 20 see the frame.
Only devices that are connected to the local switch see the frame.
Only devices in VLAN 20 see the frame.
Explanation: VLANs create logical broadcast domains that can span multiple VLAN segments. Ethernet frames that are sent by a device on a specific VLAN can only be seen by other devices in the same VLAN.
Refer to the exhibit. All workstations are configured correctly in VLAN 20. Workstations that are connected to switch SW1 are not able to send traffic to workstations on SW2. What could be done to remedy the problem?
https://itexamanswers.net/wp-content/uploads/2019/12/CCNA2-v7-SRWE-%E2%80%93-Modules-1-%E2%80%93-4-Switching-Concepts-VLANs-and-InterVLAN-Routing-Exam-Answers-29.png
Allow VLAN 20 on the trunk link.
Enable DTP on both ends of the trunk.
Configure all workstations on SW1 to be part of the default VLAN.
Configure all workstations on SW2 to be part of the native VLAN.
Allow VLAN 20 on the trunk link.
Explanation: Enabling DTP on both switches simply allows negotiation of trunking. The “Negotiation of Trunking” line in the graphic shows that DTP is already enabled. The graphic also shows how the native VLAN is 1, and the default VLAN for any Cisco switch is 1. The graphic shows the PCs are to be in VLAN 20.
What happens to switch ports after the VLAN to which they are assigned is deleted?
The ports are disabled.
The ports are placed in trunk mode.
The ports are assigned to VLAN1, the default VLAN.
The ports stop communicating with the attached devices.
The ports stop communicating with the attached devices.
Explanation: The affected ports must be reconfigured for an active VLAN.
Match the IEEE 802.1Q standard VLAN tag field with the description. (Not all options are used.)
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Explanation: The IEEE 802.1Q standard header includes a 4-byte VLAN tag:
Type – A 2-byte value called the tag protocol ID (TPID) value.
User priority – A 3-bit value that supports level or service implementation.
Canonical Format Identifier (CFI) – A 1-bit identifier that enables Token Ring frames to be carried across Ethernet links.
VLAN ID (VID) – A 12-bit VLAN identification number that supports up to 4096 VLAN IDs.
Refer to the exhibit. In what switch mode should port G0/1 be assigned if Cisco best practices are being used?
https://itexamanswers.net/wp-content/uploads/2019/12/CCNA2-v7-Modules-1-4-Switching-Concepts-VLANs-and-InterVLAN-Routing-Exam-Answers-32.png
access
trunk
native
auto
trunk
Explanation: The router is used to route between the two VLANs, thus switch port G0/1 needs to be configured in trunk mode.
Match the DTP mode with its function. (Not all options are used.)
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answer
Port Fa0/11 on a switch is assigned to VLAN 30. If the command no switchport access vlan 30 is entered on the Fa0/11 interface, what will happen?
Port Fa0/11 will be shutdown.
An error message would be displayed.
Port Fa0/11 will be returned to VLAN 1.
VLAN 30 will be deleted.
Port Fa0/11 will be returned to VLAN 1.
Explanation: When the no switchport access vlan command is entered, the port is returned to the default VLAN 1. The port will remain active as a member of VLAN 1, and VLAN 30 will still be intact, even if no other ports are associated with it.
Which command displays the encapsulation type, the voice VLAN ID, and the access mode VLAN for the Fa0/1 interface?
show vlan brief
show interfaces Fa0/1 switchport
show mac address-table interface Fa0/1
show interfaces trunk
show interfaces Fa0/1 switchport
Explanation: The show interfaces switchport command displays the following information for a given port: Switchport Administrative Mode Operational Mode Administrative Trunking Encapsulation Operational Trunking Encapsulation Negotiation of Trunking Access Mode VLAN Trunking Native Mode VLAN Administrative Native VLAN tagging Voice VLAN
Refer to the exhibit. A technician is programming switch SW3 to manage voice and data traffic through port Fa0/20. What, if anything, is wrong with the configuration?
https://itexamanswers.net/wp-content/uploads/2017/07/i297770v1n1_297770.png
There is nothing wrong with the configuration.
Interface Fa0/20 can only have one VLAN assigned.
The mls qos trust cos command should reference VLAN 35.
The command used to assign the voice VLAN to the switch port is incorrect.
The command used to assign the voice VLAN to the switch port is incorrect.
Explanation: The voice VLAN should be configured with the switchport voice vlan 150 command. A switch interface can be configured to support one data VLAN and one voice VLAN. The mls qos trust cos associates with the interface. Voice traffic must be trusted so that fields within the voice packet can be used to classify it for QoS.
Which four steps are needed to configure a voice VLAN on a switch port? (Choose four).
Configure the interface as an IEEE 802.1Q trunk.
Assign the voice VLAN to the switch port.
Activate spanning-tree PortFast on the interface.
Ensure that voice traffic is trusted and tagged with a CoS priority value.
Add a voice VLAN.
Configure the switch port interface with subinterfaces.
Assign a data VLAN to the switch port.
Configure the switch port in access mode.
Assign the voice VLAN to the switch port.
Ensure that voice traffic is trusted and tagged with a CoS priority value.
Add a voice VLAN.
Configure the switch port in access mode.
Explanation: To add an IP phone, the following commands should be added to the switch port:
SW3(config-vlan)# vlan 150
SW3(config-vlan)# name voice
SW3(config-vlan)# int fa0/20
SW3(config-if)# switchport mode access
SW3(config-if)# mls qos trust cos
SW3(config-if)# switchport access vlan 150
Refer to the exhibit. PC1 is unable to communicate with server 1. The network administrator issues the show interfaces trunk command to begin troubleshooting. What conclusion can be made based on the output of this command?
https://itexamanswers.net/wp-content/uploads/2019/12/CCNA2-v7-Modules-1-4-Switching-Concepts-VLANs-and-InterVLAN-Routing-Exam-Answers-38.jpg
Interface G0/2 is not configured as a trunk.
VLAN 20 has not been created.
The encapsulation on interface G0/1 is incorrect.
The DTP mode is incorrectly set to dynamic auto on interface G0/1.
Interface G0/2 is not configured as a trunk.
Explanation: In the show interfaces trunk output, the G0/2 interface of DLS1 is not listed. This indicates the interface has probably not been configured as a trunk link. In the show interfaces trunk output, the G0/2 interface of DLS1 is not listed. This indicates the interface has probably not been configured as a trunk link.
Refer to the exhibit. What is the cause of the error that is displayed in the configuration of inter-VLAN routing on router CiscoVille?
https://itexamanswers.net/wp-content/uploads/2019/12/CCNA2-v7-Modules-1-4-Switching-Concepts-VLANs-and-InterVLAN-Routing-Exam-Answers-39.png
The gig0/0 interface does not support inter-VLAN routing.
The no shutdown command has not been configured.
The IP address on CiscoVille is incorrect.
The encapsulation dot1Q 20 command has not been configured.
The encapsulation dot1Q 20 command has not been configured.
Refer to the exhibit. A network administrator has configured router CiscoVille with the above commands to provide inter-VLAN routing. What command will be required on a switch that is connected to the Gi0/0 interface on router CiscoVille to allow inter-VLAN routing?
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switchport mode access
no switchport
switchport mode trunk
switchport mode dynamic desirable
switchport mode trunk
Explanation: When they are configured for inter-VLAN routing, routers do not support the dynamic trunking protocol that is used by switches. For router-on-a-stick configurations to function, a connected switch must use the command switchport mode trunk.
A high school uses VLAN15 for the laboratory network and VLAN30 for the faculty network. What is required to enable communication between these two VLANs while using the router-on-a-stick approach?
A multilayer switch is needed.
A router with at least two LAN interfaces is needed.
Two groups of switches are needed, each with ports that are configured for one VLAN.
A switch with a port that is configured as a trunk is needed when connecting to the router.
A switch with a port that is configured as a trunk is needed when connecting to the router.
Explanation: With router-on-a-stick, inter-VLAN routing is performed by a router with a single router interface that is connected to a switch port configured with trunk mode. Multiple subinterfaces, each configured for a VLAN, can be configured under the single physical router interface. Switches can have ports that are assigned to different VLANs, but communication between those VLANs requires routing function from the router. A multilayer switch is not used in a router-on-a-stick approach to inter-VLAN routing.
