350-401 VLANs and Trunking Practice Test 2 — 15 Questions

Question 1

A network engineer runs the following command on Switch SW1:

SW1# show interfaces gi0/1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Gi0/1      desirable    n-802.1q       trunking      1

Port        Vlans allowed on trunk
Gi0/1       1-1005

Port        Vlans allowed and active in management domain
Gi0/1       1,10,20

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/1       1,10,20

Based on this output, what can be concluded?

Accepted Answer

VLANs 2-9 are allowed but not active.. The output shows that VLANs 1-1005 are allowed on the trunk, but only VLANs 1, 10, and 20 are active in the management domain. This means VLANs 2-9 and 11-19, 21-1005 are allowed but not active (i.e., not created or not present on the switch). Option C correctly identifies that VLANs 2-9 are among those allowed but not active.

Answer

The interface is configured as an access port.

Answer

The trunk is using ISL encapsulation.

Answer

The native VLAN is 10.

Question 2

A network engineer runs the following command on Switch SW1:

SW1# show dtp interface gi0/1

DTP information on GigabitEthernet0/1:
  DTP:                      Enabled
  DTP mode:                 Desirable
  DTP negotiate:            TRUE
  DTP status:               Trunk
  DTP trunk status:         Trunking
  DTP timer:                30
  DTP max-age:              2
  DTP encapsulation:        802.1q
  DTP refresh rate:         Both
  DTP requests:             10
  DTP errors:               0

Based on this output, what can be concluded?

Accepted Answer

The interface will not form a trunk unless the neighbor is set to trunk or desirable.. The output shows DTP mode is 'Desirable' and DTP status is 'Trunking', meaning the interface is actively attempting to form a trunk. In DTP, a switchport in desirable mode will only successfully negotiate a trunk if the neighboring interface is configured as trunk (on) or desirable; if the neighbor is in access mode or dynamic auto, the trunk will not form. Therefore, option B is correct.

Answer

The interface is in access mode.

Answer

The interface is using ISL encapsulation.

Answer

DTP is disabled on this interface.

Question 3

A network engineer runs the following command on Switch SW1:

SW1# show interfaces gi0/1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Gi0/1      on           802.1q         trunking      1

Port        Vlans allowed on trunk
Gi0/1       10,20

Port        Vlans allowed and active in management domain
Gi0/1       10,20

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/1       10,20

Based on this output, what can be concluded?

Accepted Answer

Only VLANs 10 and 20 are allowed on this trunk.. The output shows that the 'Vlans allowed on trunk' list contains only VLANs 10 and 20. This means the trunk has been explicitly configured to permit only those VLANs, and all other VLANs (including VLAN 1) are pruned or blocked from traversing the trunk. Therefore, only VLANs 10 and 20 are allowed, making option C correct.

Answer

VLAN 1 is allowed on this trunk.

Answer

The trunk is using DTP dynamic desirable mode.

Answer

The native VLAN is 10.

Question 4

Given the following configuration on a Cisco IOS-XE switch:

interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk native vlan 999
 switchport trunk allowed vlan 10,20,30

What is the effect of this configuration?

Accepted Answer

The interface will forward traffic for VLANs 10, 20, and 30, and all untagged frames will be placed into VLAN 999.. Option A is correct because the configuration sets the interface as a trunk port, explicitly allows only VLANs 10, 20, and 30 to traverse it, and designates VLAN 999 as the native VLAN. On a trunk, the native VLAN is used for untagged frames (e.g., DTP, CDP, or any traffic sent without an 802.1Q header), so all untagged frames received or sent on this interface will be associated with VLAN 999.

Answer

The interface will forward traffic for all VLANs except 10, 20, and 30, and the native VLAN is 1.

Answer

The interface will operate as an access port in VLAN 999.

Answer

The interface will forward traffic for VLANs 10, 20, and 30, and all frames will be tagged including the native VLAN.

Question 5

Examine the following configuration snippet on a Cisco IOS switch:

interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 50
 spanning-tree portfast

Which statement is true about this interface?

Accepted Answer

The interface will immediately forward traffic without any spanning-tree delay.. The `spanning-tree portfast` command on an access port configured with `switchport mode access` and `switchport access vlan 50` causes the interface to bypass the normal spanning-tree listening and learning states. This allows the port to transition directly to the forwarding state, enabling immediate traffic forwarding without the usual 30-second delay (15 seconds for listening, 15 seconds for learning) associated with Rapid Spanning Tree Protocol (RSTP) or the 50-second delay with classic STP (802.1D).

Answer

The interface will participate in trunking and forward multiple VLANs.

Answer

The interface will still go through listening and learning states before forwarding.

Answer

The interface will only forward traffic for VLAN 1.

Question 6

Consider the following configuration on a Cisco IOS-XE switch:

interface GigabitEthernet0/3
 switchport trunk encapsulation dot1q
 switchport mode trunk
 switchport trunk native vlan 1

What is the effect of this configuration?

Accepted Answer

The interface will operate as an 802.1Q trunk, and untagged frames will be associated with VLAN 1.. The configuration sets the interface to 802.1Q trunking mode and explicitly defines VLAN 1 as the native VLAN. On an 802.1Q trunk, the native VLAN is the VLAN to which untagged frames are assigned when received on the trunk port. Since VLAN 1 is the default native VLAN and is explicitly configured here, untagged frames will be associated with VLAN 1, allowing them to traverse the trunk without an 802.1Q tag.

Answer

The interface will operate as an ISL trunk.

Answer

The interface will drop all untagged frames.

Answer

The interface will only forward traffic for VLAN 1.

Question 7

Given the following configuration on a Cisco IOS switch:

interface GigabitEthernet0/4
 switchport mode trunk
 switchport trunk allowed vlan except 100-200

What is the effect of this configuration?

Accepted Answer

The trunk will forward traffic for all VLANs except VLANs 100 through 200.. The 'switchport trunk allowed vlan except 100-200' command explicitly removes VLANs 100 through 200 from the allowed VLAN list on the trunk. All other VLANs (1-99 and 201-4094) remain permitted. This is the standard behavior of the 'except' keyword in Cisco IOS trunk configuration.

Answer

The trunk will only forward traffic for VLANs 100 through 200.

Answer

The trunk will forward traffic for all VLANs.

Answer

The trunk will not forward any traffic because the allowed list is empty.

Question 8

Examine the following configuration on a Cisco IOS-XE switch:

interface GigabitEthernet0/5
 switchport mode trunk
 switchport trunk native vlan 999
 switchport trunk allowed vlan 10,20,30
 switchport nonegotiate

What is the effect of the 'switchport nonegotiate' command?

Accepted Answer

The interface will not send or process DTP frames, and remains a trunk.. The 'switchport nonegotiate' command disables Dynamic Trunking Protocol (DTP) on the interface. When configured on a trunk port, the interface will neither send nor process any DTP frames, ensuring the port remains in trunk mode regardless of the neighbor's DTP configuration. This is commonly used when connecting to non-Cisco devices that do not support DTP, or to prevent unwanted trunk negotiation.

Answer

The interface will not send DTP frames, but will still respond to incoming DTP frames.

Answer

The interface will revert to an access port.

Answer

The interface will negotiate trunking using ISL instead of DTP.

Question 9

Given the following configuration on a Cisco IOS switch:

interface GigabitEthernet0/6
 switchport mode dynamic desirable

What is the effect of this configuration?

Accepted Answer

The interface will actively try to form a trunk and will succeed if the other side is set to trunk, desirable, or auto.. The `switchport mode dynamic desirable` command configures the interface to actively send Dynamic Trunking Protocol (DTP) frames to negotiate trunking. If the neighboring interface is set to trunk, dynamic desirable, or dynamic auto, the negotiation will succeed and the link will become a trunk. This is because dynamic desirable actively initiates the negotiation, unlike dynamic auto which only responds.

Answer

The interface will only become a trunk if the other side is set to trunk.

Answer

The interface will always remain an access port.

Answer

The interface will not send DTP frames.

Question 10

What is the default native VLAN on a Cisco switch trunk port?

Accepted Answer

VLAN 1. The default native VLAN on a Cisco switch trunk port is VLAN 1. The native VLAN is the VLAN that carries untagged traffic over a trunk link, and by default, all switch ports (including trunk ports) belong to VLAN 1. This is defined in the IEEE 802.1Q standard, which specifies that frames on the native VLAN are not tagged with a VLAN ID.

Answer

VLAN 0

Answer

VLAN 1002

Answer

VLAN 4095

Question 11

Which of the following is a valid VLAN range that can be created on a Cisco IOS switch?

Accepted Answer

VLAN 100. VLAN 100 is a valid VLAN ID because Cisco IOS switches support VLANs in the range 1–1005 for normal-range VLANs, and VLAN 100 falls within this range. Normal-range VLANs are stored in the vlan.dat file and can be created on a standard IOS switch without requiring extended VLAN configuration.

Answer

VLAN 0

Answer

VLAN 4095

Answer

VLAN 1006

Question 12

What is the purpose of the Dynamic Trunking Protocol (DTP) on Cisco switches?

Accepted Answer

To automatically negotiate trunking between two Cisco switches.. DTP (Dynamic Trunking Protocol) is a Cisco proprietary protocol used to automatically negotiate the operational mode (access or trunk) of a switch port between two Cisco switches. When both ends are configured with DTP modes like dynamic desirable or dynamic auto, the link can become a trunk without manual configuration, simplifying deployment in environments where trunking is needed.

Answer

To dynamically assign VLANs to access ports.

Answer

To provide security by encrypting trunk traffic.

Answer

To prevent loops in the network.

Question 13

Drag and drop the steps of Dynamic Trunking Protocol (DTP) negotiation into the correct order, from first to last.

Accepted Answer

Set interface to switchport mode trunk. DTP negotiation begins with the interface defaulting to dynamic desirable or auto mode. If a switchport is set to trunk, DTP sends frames to negotiate. The neighbor responds if in a compatible mode. Once agreed, the link becomes trunking. Finally, both ends forward traffic for multiple VLANs.

Question 14

Drag and drop the steps of configuring a native VLAN mismatch detection into the correct order, from first to last.

Accepted Answer

Configure native VLAN 10 on trunk interface. First, configure the trunk interface with a specific native VLAN. Then, set the neighbor's trunk to a different native VLAN. The mismatch causes CDP to log an error. The switch then disables the trunk port. Finally, the administrator corrects the native VLAN to match.

Question 15

Drag and drop the steps of adding a new VLAN to a trunk link into the correct order, from first to last.

Accepted Answer

Create VLAN 100 in global configuration. First, create the VLAN globally on the switch. Then, verify the VLAN exists. Next, ensure the trunk allows that VLAN. After that, check the trunk's allowed VLAN list. Finally, test connectivity for hosts in the new VLAN.