Practice Q's - INTER-VLAN Flashcards
A company has a following network infrastructure. Refer to the exhibit:
To enable inter-VLAN routing on the distribution layer switch, which of the following commands should be used?
A. dlswitch# switchport mode access
B. dlswitch (config) # switchport mode trunk
C. dlswitch(config-if) # switchport mode trunk
D. dlswitch(config-if) # switchport mode access
Answer: C
Explanation:
You should use switchport mode trunk command at the interface configuration prompt to enable inter-VLAN routing. This command sets the port as a trunk port. Trunks carry traffic from all VLANs to and from the switch by default, and can be configured to carry specific VLAN traffic as well.
A port on a Cisco switch is either an access port or a trunk port. An access port only carries traffic for the VLAN of which it is a member and does not tag or mark the frame with a VLAN ID. A trunk port carries traffic from multiple VLANs and tags or marks each frame with a VLAN ID so it can be determined where it goes when it gets to the other switch.
You can enable inter-VLAN routing by enabling trunking using the following command: switchport mode trunk
You would not use the dlswitch# switchport mode access command to enable inter-VLAN routing. This command sets the port as an access port, which is capable of carrying only the traffic a single VLAN. Moreover, even if that were the intent, the command must be executed in interface mode and not global configuration mode.
You would not use the dlswitch (config) # switchport mode trunk command to enable inter-VLAN routing. This is the correct command, but is shown being executed in global configuration mode instead of interface mode.
You would not use the dlswitch(config-if)# switchport mode access command to enable inter- VLAN routing. This is both the wrong command and is being executed at an incorrect prompt.
Which devices are required to provide connectivity between VLANs? (Choose two.)
A. hub
B. router
C. bridge
D. multilayer switch
E. DSU/CSU
Answer: B,D
Explanation:
Routing between different VLANs can be accomplished using VLAN-capable multilayer switches or routers.
Devices within a single VLAN can communicate without the aid of a Layer 3 device, but as a rule, devices in different VLANs require a Layer 3 device for communication. The only situation where two computers in different VLANs located on different switches can ping one another is if they have addresses in the same subnet, and if the link between the two switches is an access port rather than trunk port.
Since traffic is sent untagged in an access link, if the link between the switches is an access link and the computers are in the same subnet, they will be able to ping one another. The following steps can be used to configure inter-VLAN routing on a multilayer switch:
- Enable IP routing. switch(config)# ip routing
Note: Routing must be enabled on a Layer 3 switch for interVLAN routing to occur. This can be verified by examining the output of the show run command executed on the switch. The example below is output from the show run command executed on a switch that has IP routing enabled, as can be seen in the third line (ip routing):
- Specify an IP routing protocol, such as RIP. switch(config)# router rip
- Specify a VLAN interface. switch(config)# interface vlan vlanid
- Assign an IP address to the VLAN. switch(config-if)# ip address address subnet-mask
Hubs operate at the Physical layer (Layer 1) and do not have the ability to route. Bridges operate at the Data Link layer (Layer 2) and do not have the ability to route.
CSU/DSUs convert signals from a LAN to a type necessary for the telco. They do not have the ability to route.
Which command do you use on a switch to put an interface that is in Layer 3 mode into Layer 2 mode?
A. vlan
B. no vlan
C. switchport
D. no switchport
Answer: C
Explanation:
Use the switchport command to put an interface that is in Layer 3 mode into Layer 2 mode.
- switch(config-if)# switchport
Use the no switchport command to remove Layer 2 configurations and return an interface to Layer 3 mode.
- switch(config-if)# no switchport
The enhanced multilayer switch image must be installed on the switch to use this command.
The vlan vlan-id configuration command is used to configure VLAN characteristics for a specific VLAN. Use the no keyword without additional parameters to delete a VLAN.
What information is displayed by the command switch# show ip interface brief?
A. a summary of the IP addresses and subnet mask on the interface
B. a summary of the IP addresses on the interface and the interface’s status
C. the IP packet statistics for the interfaces
D. the IP addresses for the interface and the routing protocol advertising the network
Answer: B
Explanation:
The command show ip interface brief displays a summary of the IP address on the interface and the interface’s status. The status means whether the interface is up. This command is useful whenyou are connected a router or switch with which you are not familiar, because it allows you to obtain the state of all interfaces or switch ports. Sample output is shown below:
This command does not display subnet mask information. Use other commands, such as show ip interface or show run interface, to verify the subnet mask.
IP statistics about the interface are displayed with the command show ip interface. Adding the brief keyword tells the switch to leave out everything but the state of the interface and its IP address.
To view the routing protocol advertising an interfaces network, you would use the command show ip protocol.
Which IOS command do you use to remove Layer 2 configurations and return an interface to Layer 3 mode?
A. vlan
B. no vlan
C. switchport
D. no switchport
Answer: D
Explanation:
Use the no switchport command to remove Layer 2 configurations and return an interface to Layer 3 mode. The syntax of the command is:
- switch(config-if)# no switchport
The enhanced multilayer switch image must be installed on the switch to use this command.
The switchport command without the no keyword converts the port back to a Layer 2-switched interface.
- switch(config-if)# switchport
The vlan vlan-id configuration command is used to configure VLAN characteristics for a specific VLAN. Use the no keyword without additional parameters to delete a VLAN.
Refer to the following network diagram:
You executed the following commands on the swtA switch:
Which of the following VLANs do(es) NOT participate in inter-VLAN routing through the rtrA router?
A. VLAN 11 only
B. VLAN 22 only
C. VLAN 33 only
D. VLAN 11 and VLAN 22
E. VLAN 22 and VLAN 33
F. VLAN 33 and VLAN 11
Answer: B
Explanation:
VLAN 22 is the only VLAN that does not participate in inter-VLAN routing through the rtrA router. The given network diagram and the commands reflect a router-on-a-stick (RoaS) configuration. In a RoaS configuration, inter-VLAN routing is achieved in two steps.
The first step sets up the switch:
The second step sets up the router:
In the scenario, the subinterface created for VLAN 22 is not configured for inter-VLAN routing because the encapsulation command is missing. Without this command, the encapsulation type and the VLAN ID remain
What information is displayed by the command switch# show ip interface brief?
A. a summary of the IP addresses and subnet mask on the interface
B. a summary of the IP addresses on the interface and the interface’s status
C. the IP packet statistics for the interfaces
D. the IP addresses for the interface and the routing protocol advertising the network
Answer: B
Explanation:
The command show ip interface brief displays a summary of the IP address on the interface and the interface’s status. The status means whether the interface is up. This command is useful when you are connected to a router or switch with which you are not familiar, because it allows you to obtain the state of all interfaces or switch ports. Sample output is shown below:
This command does not display subnet mask information. Use other commands, such as show ip interface or show run interface, to verify the subnet mask.
IP statistics about the interface are displayed with the command show ip interface. Adding the brief keyword tells the switch to leave out everything but the state of the interface and its IP address.
To view the routing protocol advertising an interfaces network, you would use the command show ip protocol.
Consider the following commands executed on a Layer 3 switch named switchA:
Which of the following physical interfaces do NOT affect the uplink state of VLAN 10? (Choose two.)
A. Fa0/1
B. Fa0/2
C. Fa0/3
D. Fa0/4
Answer: B,C
Explanation:
The Fa0/2 and Fa0/3 physical interfaces of switchA do not affect the uplink state of VLAN 10. This is because the switchport autostate exclude command is used on the Fa0/2 and Fa0/3 interfaces. This command causes the exclusion of an interface from the determination of the uplink state of the VLAN (SVI interface) to which the interface belongs.
An SVI or switch virtual interface is a logical interface that allows you to enable inter-VLAN routing on Layer 3 switches. SVIs are configured as VLAN interfaces and have at least one physical interface assigned to the VLANs. An SVI is up and running when all of the following conditions are met:
When an SVI services multiple interfaces (the switch ports in the VLAN to which the SVI connects) and all of them go down, the SVI also goes down by default. When any of the interfaces comes up, the SVI also comes up. By default, all interfaces assigned to the SVI are involved in determining its uplink state. However, if you do not want a particular interface to participate in this determination, use the switchport autostate exclude command on that interface.
You can use the switchport autostate exclude command on any Layer 2 access or trunk interface. This command applies to all VLANs to which the interface belongs. If the excluded interface of an SVI is in the up state and all the other interfaces of the SVI are in the down state, the SVI remains in the down state. The state of the SVI does not change to up.
The Fa0/1 and Fa0/4 interfaces of switchA affect the uplink state of VLAN 10 because all the interfaces assigned to an SVI contribute towards the uplink state determination of the SVI by default.
