Term
| Why is it generally a good idea to split up a large network into smaller networks? |
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Definition
| Splits up broadcast domains, which cuts down traffic and should improve performance. Allows different groups of users to have different facilities and security regimes. |
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Term
| What is the advantage of implementing subnets as VLANs rather than using routers to separate subnets? |
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Definition
| VLANs can be implemented using switches, which are cheaper and operate more quickly that routers. (Though a layer 3 device such as a router is still needed to routetraffic between VLANs.) A VLAN can be implemented across several switches indifferent locations, so that a group of users with the same requirements does not haveto be all together in the same place. |
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Term
| How many VLANs can there be on a Catalyst 2600 series switch? |
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Definition
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Term
| Which VLANs exist by default on a Catalyst 2950 switch, and which of these are intended for Ethernet networks? |
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Definition
| VLAN 1 is for Ethernet. VLANs 1002 to 1005 also exist, but are for use on Token Ring or FDDI networks. |
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Term
| If you create a normal range VLAN, where will the information about it be stored? |
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Definition
| In a file called vlan.dat which is in flash memory. (Not in the running or startupconfiguration.) |
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Term
| A new Catalyst switch has not yet been configured. Are the Ethernet ports associated with any VLAN? If so, which one? |
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Definition
| By default, all Ethernet ports are in VLAN 1. |
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Term
| Should you configure the switch IP address on VLAN 1? |
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Definition
| You could, but it is better for security reasons to create another VLAN to be the management VLAN and assign the IP address to it. This management VLAN will beused only for managing the switch via Telnet, SSH or the web based interface |
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Term
| What name is given to the type of VLAN that carries normal user traffic such as files,downloads and e-mails? |
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Definition
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Term
| Which type of VLAN needs special configuration so that its traffic has priority over other traffic? |
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Definition
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Term
| What are the two methods of assigning an end device to a VLAN, and which method ismore common? (Assume that voice traffic is not required.) |
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Definition
| Port based or static VLANs are configured on switch ports and a device connecting to a port belongs to the VLAN configured on that port. Dynamic VLANs assign devices toVLANs using the MAC addresses of the devices, and these VLAN to MAC addressmatches need to be stored on a server. Static VLANs are more common. |
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Term
| A PC attached to a switch sends out a broadcast ARP request. Which devices willreceive the ARP request? |
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Definition
| Devices on the same VLAN as the PC. |
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Term
| Which devices allow inter-VLAN communication? |
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Definition
| Routers or layer 3 switches. |
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Term
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Definition
| A link that carries traffic for more than one VLAN. It is a point to point link between two switches or between a switch and a router. |
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Term
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Definition
| It is a method of adding information to a frame to show which VLAN the frame belongs to. It is used only on VLAN trunk links. |
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Term
| Which protocol is now most commonly used for frame tagging, and which other protocolmay still be in use? |
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Definition
| IEEE 802.1Q is now the common protocol. Inter Switch Link (ISL) is a Cisco proprietary protocol that is no longer supported by newer Cisco switches, but may still be in use |
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Term
| What is the purpose of the EtherType field in a frame, which is set to the hexadecimalvalue of 0x8100? |
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Definition
| It signals to the device receiving the frame that this is a tagged IEEE 802.1Q framecontaining VLAN information. If the frame were untagged then the device would find thelength/type field in this position. |
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Term
| What does a switch port on a trunk link do if it receives a frame without a tag? |
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Definition
| Forwards it on to the native VLAN. By default this is VLAN 1, but usually a different native VLAN is configured on a trunk link. |
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Term
| Why can native VLANs and VLAN trunks give problems when Cisco devices and non-Cisco devices are mixed on a network? |
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Definition
| Cisco devices do not tag frames from the native VLAN when forwarding them on a trunk link, but some non-Cisco devices do tag them. By default, Cisco switches drop tagged frames destined for the native VLAN, so frames from non-Cisco devices may bedropped. |
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Term
| How can you configure the fastethernet interface fa0/1 of switch SW1 to be a trunkport? |
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Definition
SW1(config)# int fa0/1
SW1(config-if)# switchport mode trunk |
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Term
| How can you configure the fastethernet interface fa0/2 of switch SW1 to be a port thathandles traffic from one VLAN only? |
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Definition
SW1(config)# int fa0/2
SW1(config-if)# switchport mode access |
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Term
| What is the purpose of Dynamic Trunking Protocol? |
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Definition
| It allows linked switches to negotiate on whether or not the link between them is a trunk link. |
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Term
| Two switches are connected. If both ends of the link are ports in dynamic auto mode,will the link be a trunk or not? |
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Definition
| No, it will be an access link. |
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Term
| Two switches are connected. If both ends of the link are ports in dynamic desirablemode, will the link be a trunk or not? |
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Definition
| Yes, it will be a trunk link. |
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Term
| What is the currently approved method of creating a VLAN, number 6, called Finance,on switch SW1? |
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Definition
SW1(config)# vlan 6
SW1(config-vlan)# name Finance |
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Term
| Which command will let you see a list of all existing VLANs and the ports that are associated with each one? |
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Definition
| Show vlan brief (or show vlan) |
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Term
| What information does the command “show vlan summary” give you? |
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Definition
| It tells you how many VLANs there are on the switch. No VLAN numbers, names or detail. |
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Term
| Which command would show you whether or not VLAN 4 is up? |
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Definition
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Term
What is the effect of the commands:
SW1(config)#int fa0/12
SW1(config-if)#no switchport access vlan
SW1(config-if)#end |
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Definition
| Interface fa 0/12 will be removed from its existing VLAN and returned to the default VLAN. (VLAN 1 unless this has been changed.) |
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Term
What is the effect of the commands:
SW1(config)#no vlan 7
SW1(config)#exit |
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Definition
| VLAN 7 is deleted. If any ports are assigned to VLAN 7 then they will become inactive.They need to be assigned to another VLAN before they can be used again. |
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Term
What is the effect of the command:
SW1(config)#delete flash:vlan.dat |
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Definition
| The VLAN database in flash memory is deleted. When the switch is reloaded, all configured VLAN information will have disappeared |
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Term
You configure interface Fa0/1 as follows:
SW1(config-if)#switchport mode trunk
Which is the native VLAN, and which VLANs can this interface handle? |
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Definition
| VLAN 1 is the native VLAN. The trunk can handle traffic belonging to all VLANs. |
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Term
| Which additional commands would you give to make VLAN 90 the native VLAN and to permit traffic belonging to VLANs 3, 4 and 5 only? |
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Definition
SW1(config-if)# switchport trunk native vlan 90
SW1(config-if)# switchport trunk allowed vlan add 3,4,5 |
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Term
| Which command would show you how interface Fa0/1 has been configured for trunking? |
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Definition
| SW1# show interfaces fa0/1 switchport |
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Term
You give the commands:
SW1(config)#int fa0/1
SW1(config-if)#no switchport trunk allowed vlan
SW1(config-if)#end
Which VLAN traffic can now pass over the trunk link? |
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Definition
| Traffic for all VLANs. (Default condition is restored.) |
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Term
| How can you stop interface Fa0/1 from being a trunk link? |
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Definition
SW1(config)# int fa0/1
SW1(config-if)# switchport mode access |
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Term
| A trunk link is not working correctly. What should you check? |
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Definition
Have the ports at both ends of the link been configured with the same native VLAN?
Are the ports at both ends of the link working as trunk links or is there a problem withtheir modes? (E.g. one of them configured as an access port or both of them in dynamic auto mode.) Are all the required VLANs allowed on the trunk at both ends? Do all the devices on a VLAN have addresses on the same subnet? |
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