6.4 Virtual LANs

You need to keep users in all other departments from accessing the servers used by the finance department. Which of the following technologies should you use to logically isolate the network?

A virtual LAN (VLAN) uses switch ports to define a broadcast domain. When you define a VLAN, you assign devices on different switch ports to a separate logical, or virtual, LAN.

Which of the following are reasons to configure VLANs on a switch as opposed to using switches without VLANs?

Create VLANs to increase the number of broadcast domains and implement security. Each VLAN is in its own broadcast domain. Broadcast traffic within the VLAN goes only to the members of the VLAN. Members of one VLAN can only communicate with members in the same VLAN through the switch. A router or a Layer 3 switch is required to enable inter-VLAN communication.

You have two VLANs configured on a single switch. How many broadcast domains are there? How many collision domains are there?

Defining VLANs creates multiple broadcast domains.

Which of the following best describes the concept of a VLAN?

Devices on the same network logically grouped as if they were on separate networks.

You manage a network with two switches. The switches are connected together through their Gigabit Ethernet uplink ports. You define VLAN 1 and VLAN 2 on each switch. A device on the first switch in VLAN 1 needs to communicate with a device on the same switch which is in VLAN 2. What should you configure so that the two devices can communicate?

In a typical configuration with multiple VLANs and a single or multiple switches, workstations in one VLAN will not be able to communicate with workstations in other VLANs. To enable inter-VLAN communication, you will need to use a router (or a Layer 3 switch).

Which of the following connectivity hardware is used to create a VLAN?

Specialized switches are used to create virtual LANs. The switch must be capable of appending and reading VLAN IDs.

What are two advantages of creating VLANs on your network?

Two advantages to creating VLANs on your network are: 1. Broadcasts are required for the normal function of a network. Many protocols and applications depend on broadcast communication to function properly. A layer 2 switched network is in a single broadcast domain and the broadcasts can reach the network segments which are so far where a particular broadcast has no scope and consume available network bandwidth. A layer 3 device is used to segment a broadcast domain. 2. VLANs provide enhanced network security. In a VLAN network environment, with multiple broadcast domains, network administrators have control over each port and user. A malicious user can no longer just plug their workstation into any switch port and sniff the network traffic using a packet sniffer.

You manage a network that uses a single switch. All ports within your building connect through the single switch. In the lobby of your building are three RJ45 ports connected to the switch. You want to allow visitors to plug into these ports to gain internet access, but they should not have access to any other devices on your private network. Employees connected throughout the rest of your building should have both private and internet access. Which feature should you implement?

Use VLANs to segregate hosts based on switch ports. You can define two VLANs, one for employees connected throughout the building, and another for the ports in the lobby. The ports in the lobby would have only internet access, while devices connected to ports in the rest of the building could communicate with other devices within the same VLAN.

You want to reduce collisions by creating separate collision domains and virtual LANs. Which of the following devices should you choose?

Use a switch to create additional collision domains on a LAN. A switch filters an entire network and creates virtual LANs inside it rather than dividing it into separate internetworks as a router does.

You can create a virtual LAN using which of the following?

Use a switch to create virtual LANs (VLANs). The various ports on a switch can be assigned to a specific VLAN to create logically distinct networks on the same physical network topology.

When you configure VLANs on a switch, which of the following is used to identify a device's VLAN membership?

VLAN membership is configured by assigning a switch port to a VLAN. A switch can have multiple VLANs configured on it, but each switch port can only be a member of a single VLAN. All devices connected to a switch port are members of the same VLAN.

Which of the following statements describe how VLANs affect broadcast traffic within an internetwork?

VLANs allow computers to be grouped into a common broadcast domain regardless of their physical location on the network. Broadcast traffic is seen only by computers belonging to the same VLAN. Devices sharing a VLAN ID must also share the same subnet address so that traffic can be routed between VLANs.

Which of the following are true regarding using multiple VLANs on a single switch?

When you configure multiple VLANs on a single switch, the number of broadcast domains increases. Each VLAN will be placed in its own broadcast domain. The number of collision domains remains the same. Each switch port is its own collision domain regardless of the number of VLANs configured on the switch.

What happens if two devices on the same switch are assigned to different VLANs?

Workstation in VLAN 1 will not be able to communicate with workstation in VALN 2, even though they are connected to the same physical switch. Communications between VLANs requires a router, just as with physical LANs.

You run a small network for your business that has a single router connected to the internet and a single switch. You keep sensitive documents on a computer that you would like to keep isolated from other computers on the network. Other hosts on the network should not be able to communicate with this computer through the switch, but you still need to access the network through the computer. Which of the following should you use in this situation?

You should define virtual LANs (VLANs) on the switch. With a VLAN, a port on the switch is associated with a VLAN. Only devices connected to ports that are members of the same VLAN can communicate with each other. Routers are used to allow communication between VLANs if necessary.

Your company is a small start-up that has leased office space in a building shared by other businesses. All businesses share a common network infrastructure. A single switch connects all devices in the building to the router that provides internet access. You would like to make sure that your computers are isolated from computers used by other companies. Which feature should you request to have implemented?

You should define virtual LANs (VLANs) on the switch. With a VLAN, a port on the switch is associated with a VLAN. Only devices connected to ports that are members of the same VLAN can communicate with each other. Routers are used to allow communication between VLANs if necessary.

VLAN ID

are appended to the header of each frame. In addition, they allow switches to identify which VLAN the frame belongs to and are used for inter-switch traffic.

VLAN

group of devices on one or more local area networks (LAN) that are configured to communicate as if they were attached to the same wire when, in fact, they could be located on a number of different LAN segments.