CCNA – Trunking Questions - Quiz, Flashcards & Trivia

1. Which IEEE standard protocol is initiated as a result of successful DTP completion in a switch over FastEthernet?

802.3ad

802.1w

802.1Q

802.1d

Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol for negotiating trunking on a link between two devices and for negotiating the type of trunking encapsulation (802.1Q) to be used.

Explanation

Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol for negotiating trunking on a link between two devices and for negotiating the type of trunking encapsulation (802.1Q) to be used.

2. In a switched environment, what does the IEEE 802.1Q standard describe?

The operation of VTP

A method of VLAN trunking

An approach to wireless LAN communication

The process for root bridge selection

VLAN pruning

The IEEE 802.1Q standard describes a method of VLAN trunking. VLAN trunking allows multiple VLANs to be carried over a single physical link, enabling efficient use of network resources and simplifying network management. This standard defines how VLAN tags are added to Ethernet frames, allowing switches to identify and separate different VLAN traffic. By using VLAN trunking, organizations can create logical networks within a physical network infrastructure, improving network efficiency and security.

Explanation

The IEEE 802.1Q standard describes a method of VLAN trunking. VLAN trunking allows multiple VLANs to be carried over a single physical link, enabling efficient use of network resources and simplifying network management. This standard defines how VLAN tags are added to Ethernet frames, allowing switches to identify and separate different VLAN traffic. By using VLAN trunking, organizations can create logical networks within a physical network infrastructure, improving network efficiency and security.

3. Refer to the exhibit:

C-router is to be used as a "router-on-a-stick" to route between the VLANs. All the interfaces have been properly configured and IP routing is operational. The hosts in the VLANs have been configured with the appropriate default gateway. What can be said about this configuration?

These commands need to be added to the configuration:C-router(config)# router eigrp 123 C-router(config-router)# network 172.19.0.0

No further routing configuration is required.

These commands need to be added to the configuration:C-router(config)# router ospf 1C-router(config-router)# network 172.19.0.0 0.0.3.255 area 0

These commands need to be added to the configuration:C-router(config)# router ripC-router(config-router)# network 172.19.0.0

The given configuration statement states that no further routing configuration is required. This means that the current configuration is sufficient for the C-router to route between the VLANs. The interfaces are properly configured, IP routing is operational, and the hosts in the VLANs have the appropriate default gateway. Therefore, there is no need to add any additional routing protocols or network statements.

Explanation

The given configuration statement states that no further routing configuration is required. This means that the current configuration is sufficient for the C-router to route between the VLANs. The interfaces are properly configured, IP routing is operational, and the hosts in the VLANs have the appropriate default gateway. Therefore, there is no need to add any additional routing protocols or network statements.

4. Refer to the exhibit:

All switch ports are assigned to the correct VLANs, but none of the hosts connected to SwitchA can communicate with hosts in the same VLAN connected to SwitchB. Based on the output shown, what is the most likely problem?

The access link needs to be configured in multiple VLANs.

The link between the switches is configured in the wrong VLAN

The link between the switches needs to be configured as a trunk.

VTP is not configured to carry VLAN information between the switches.

Switch IP addresses must be configured in order for traffic to be forwarded between the switches.

Based on the output shown, the most likely problem is that the link between the switches needs to be configured as a trunk. This is because the output shows that the interface between the switches is in access mode, which means it can only carry traffic for a single VLAN. In order for hosts in different VLANs to communicate with each other, the link between the switches needs to be configured as a trunk, which can carry traffic for multiple VLANs.

Explanation

Based on the output shown, the most likely problem is that the link between the switches needs to be configured as a trunk. This is because the output shows that the interface between the switches is in access mode, which means it can only carry traffic for a single VLAN. In order for hosts in different VLANs to communicate with each other, the link between the switches needs to be configured as a trunk, which can carry traffic for multiple VLANs.

5. What are the possible trunking modes for a switch port? (Choose three)

Transparent

Auto

On

Desirable

Client

Forwarding

The possible trunking modes for a switch port are auto, on, and desirable. Auto mode allows the switch port to negotiate with the connected device to determine if trunking should be enabled. On mode forces the switch port to become a trunk port regardless of the connected device. Desirable mode actively tries to negotiate trunking with the connected device, but if it fails, it falls back to a non-trunking mode.

Explanation

The possible trunking modes for a switch port are auto, on, and desirable. Auto mode allows the switch port to negotiate with the connected device to determine if trunking should be enabled. On mode forces the switch port to become a trunk port regardless of the connected device. Desirable mode actively tries to negotiate trunking with the connected device, but if it fails, it falls back to a non-trunking mode.

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6. As a network technician, do you know which are valid modes for a switch port used as a VLAN trunk? (Choose three)

Transparent

Auto

On

Desirable

Blocking

Forwarding

The valid modes for a switch port used as a VLAN trunk are auto, on, and desirable. The "auto" mode allows the port to negotiate and become a trunk if the connected device supports it. The "on" mode forces the port to become a trunk regardless of the connected device. The "desirable" mode actively tries to negotiate and become a trunk, but falls back to a non-trunking mode if the other end does not support it.

Explanation

The valid modes for a switch port used as a VLAN trunk are auto, on, and desirable. The "auto" mode allows the port to negotiate and become a trunk if the connected device supports it. The "on" mode forces the port to become a trunk regardless of the connected device. The "desirable" mode actively tries to negotiate and become a trunk, but falls back to a non-trunking mode if the other end does not support it.

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7. Refer to the topology and router output shown in the exhibit:

A technician is troubleshooting host connectivity issues on the switches. The hosts in VLANs 10 and 15 on Sw11 are unable to communicate with hosts in the same VLANs on Sw12. Hosts in the Admin VLAN are able to communicate. The port-to-VLAN assignments are identical on the two switches. What could be the problem?

The Fa0/1 port is not operational on one of the switches.

The Link connecting the switches has not been configured as a trunk.

Port FastEthernet 0/1 needs to be configured as an access link on both switches.

The show vlan command only displays access ports, the trunk ports are not shown in this command (we can use the “show interface trunk” command to see trunked ports). In the output we can see the ports Fa0/1 connecting between two switches in VLAN 20 -> they are access ports and only VLAN 20 can communicate. To make all VLANs can communicate (with the same VLAN at the other switch), the link between two switches must be set as trunk -> B is correct.

Explanation

The show vlan command only displays access ports, the trunk ports are not shown in this command (we can use the “show interface trunk” command to see trunked ports). In the output we can see the ports Fa0/1 connecting between two switches in VLAN 20 -> they are access ports and only VLAN 20 can communicate. To make all VLANs can communicate (with the same VLAN at the other switch), the link between two switches must be set as trunk -> B is correct.

8. Refer to the exhibit:

What commands must be configured on the 2950 switch and the router to allow communication between host 1 and host 2? (Choose two)

Router(config)#interface fastethernet 0/0Router(config-if)#ip address 192.168.1.1 255.255.255.0 Router(config-if)#no shut down

Router(config)#interface fastethernet 0/0Router(config-if)#no shutdownRouter(config)#interface fastethernet 0/0.1Router(config-subif)#encapsulation dot1q 10Router(config-subif)#ip address 192.168.10.1 255.255.255.0Router(config-subif)#interface fastethernet 0/0.2Router(config-subif)#encapsulation dot1q 20Router(config-subif)#ip address 192.168.20.1 255.255.255.0

Router (config)#router eigrp 100Router(config-router)#network 192.168.10.0 Router(config-router)#network 192.168.20.0

Switch1(config)# vlan databaseSwitch1(config-vlan)# vtp domain XYZ Switch1(config-vlan)# vtp server

Switch1(config) # interface fastEthernet 0/1Switch1(config-if)# switchport mode trunk

Switch1(config)# interface vlan 1Switch1(config-if)# ip default-gateway 192.168.1.1

To allow communication between host 1 and host 2, the following commands must be configured:

On the router:
1. Enable the interface FastEthernet 0/0 with the "no shutdown" command.
2. Create subinterfaces FastEthernet 0/0.1 and FastEthernet 0/0.2 with VLAN encapsulation using the "encapsulation dot1q" command.
3. Assign IP addresses 192.168.10.1/24 and 192.168.20.1/24 to the respective subinterfaces.

On the switch:
1. Configure the switchport connected to the router's FastEthernet 0/0 as a trunk port using the "switchport mode trunk" command.

These configurations will allow traffic to pass between the hosts on VLANs 10 and 20 through the trunk link between the switch and the router.

Explanation

To allow communication between host 1 and host 2, the following commands must be configured:

On the router:
1. Enable the interface FastEthernet 0/0 with the "no shutdown" command.
2. Create subinterfaces FastEthernet 0/0.1 and FastEthernet 0/0.2 with VLAN encapsulation using the "encapsulation dot1q" command.
3. Assign IP addresses 192.168.10.1/24 and 192.168.20.1/24 to the respective subinterfaces.

On the switch:
1. Configure the switchport connected to the router's FastEthernet 0/0 as a trunk port using the "switchport mode trunk" command.

These configurations will allow traffic to pass between the hosts on VLANs 10 and 20 through the trunk link between the switch and the router.

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9. Which three of these statements regarding 802.1Q trunking are correct? (Choose three)

802.1Q native VLAN frames are untagged by default.

802.1Q trunking ports can also be secure ports.

802.1Q trunks can use 10 Mb/s Ethernet interfaces.

802.1Q trunks require full-duplex, point-to-point connectivity.

802.1Q trunks should have native VLANs that are the same at both ends.

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Explanation

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10. Which two of these are characteristics of the 802.1Q protocol? (Choose two)

It is a layer 2 messaging protocol which maintains vlan configurations across network.

It includes an 8-bit field which specifies the priority of a frame.

It is used exclusively for tagging vlan frames and does not address network reconvergence following switched network topology changes.

It modifies the 802.3 frame header and thus requires that the FCS be recomputed.

It is a trunking protocol capable of earring untagged frames.

IEEE 802.1Q is the networking standard that supports Virtual LANs (VLANs) on an Ethernet network. It is a protocol that allows VLANs to communicate with one another using a router. 802.1Q trunks support tagged and untagged frames.

If a switch receives untagged frames on a trunk port, it believes that frame is a part of the native VLAN. Also, frames from a native VLAN are not tagged when exiting the switch via a trunk port.

The 802.1q frame format is same as 802.3. The only change is the addition of 4 bytes fields. That additional header includes a field with which to identify the VLAN number. Because inserting this header changes the frame, 802.1Q encapsulation forces a recalculation of the original FCS field in the Ethernet trailer.

Note: Frame Check Sequence (FCS) is a four-octet field used to verify that the frame was received without loss or error. FCS is based on the contents of the entire frame.

Explanation

IEEE 802.1Q is the networking standard that supports Virtual LANs (VLANs) on an Ethernet network. It is a protocol that allows VLANs to communicate with one another using a router. 802.1Q trunks support tagged and untagged frames.

If a switch receives untagged frames on a trunk port, it believes that frame is a part of the native VLAN. Also, frames from a native VLAN are not tagged when exiting the switch via a trunk port.

The 802.1q frame format is same as 802.3. The only change is the addition of 4 bytes fields. That additional header includes a field with which to identify the VLAN number. Because inserting this header changes the frame, 802.1Q encapsulation forces a recalculation of the original FCS field in the Ethernet trailer.

Note: Frame Check Sequence (FCS) is a four-octet field used to verify that the frame was received without loss or error. FCS is based on the contents of the entire frame.

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