Proof knowledge questions on VLAN technology (questions and answers) Question 1 Please select the true statements regarding the use of VLANs to segment a network? (select three) A. Increase the size of collision domains B. Allow logical grouping of users by function. C. Can enhance network security. D. Increase the size of the broadcast domain while decreasing the number of collision domains. E. Increase the number of broadcast domains while decreasing the size of the broadcast domains. F. They simplify switch administration. Answer: B, C, E Explanation : VLANs are used to segment a LAN into multiple, smaller LANs. This can be used to enhance security as local traffic from one VLAN will not be passed to users in other VLANs. Incorrect Answers : A => VLANs are used to decrease the size of a collision domain, and not to increase it. D => The opposite is true. F => The default operation of a switch is to allow all traffic and to enable all ports in VLAN Note: The use of VLANs will increase the complexity of the switch environment, leading to more difficult management of it. 1 Question 2 A switch is configured with all ports assigned to VLAN 2. In addition, all ports are configured as full-duplex Fast Ethernet. What is the effect of adding switch ports to a new VLAN on this switch? A. The additions will create more collisions domains. B. IP address utilization will be more efficient. C. More bandwidth will be required than was needed previously. D. An additional broadcast domain will be created. E. The possibility that switching loops will occur will increase dramatically. Answer: D Explanation : A VLAN is a group of hosts with a common set of requirements that communicate as if they were attached to the same wire, regardless of their physical location. A VLAN has the same attributes as a physical LAN, but it allows for end stations to be grouped together even if they are not located on the same LAN segment. Networks that use the campus-wide or end-to-end VLANs logically segment a switched network based on the functions of an organization, project teams, or applications rather than on a physical or geographical basis. For example, all workstations and servers used by a particular workgroup can be connected to the same VLAN, regardless of their physical network connections or interaction with other workgroups. Network reconfiguration can be done through software instead of physically relocating devices. Cisco for instance recommends the use of local or geographic VLANs that segment the network based on IP subnets. Each wiring closet switch is on its own VLAN or subnet and traffic between each switch is routed by the router. A VLAN can be thought of as a broadcast domain that exists within a defined set of switches. Ports on a switch can be grouped into VLANs in order to limit unicast, multicast, and broadcast traffic flooding. Flooded traffic originating from a particular VLAN is only flooded out ports belonging to that VLAN, including trunk ports, so a switch that connects to another switch will normally introduce an additional broadcast domain. 2 Question 3 The network manager wishes to segment a LAN into multiple broadcast domains. Which technology method should be used in order to do this? A. Transparent bridging B. Cut-through switching C. Fragment-free switches D. Virtual LANs E. Store-and-forward switching F. None of the above Answer: D Explanation : The creation of VLANs in a switch will provide separate Broadcast domains. By default, all ports in a switch usually belong to VLAN1. By creating additional VLANs, the LAN will be logically segmented into separate broadcast domains. Incorrect Answers : A => Transparent bridging is called Transparent because the endpoints devices do not need to know that the bridges exists. It will not play any role for creating separate broadcast domain B, E => Both of these are switching methods. C => This has nothing to do with the creation of multiple broadcast domains. Question 4 One of the vhb exercise has implemented the use of VLANs. Which of the following are considered to be a benefit of VLANs? (choose three) A. They increase the size of collision domains. B. They allow logical grouping of users by function. C. They can enhance network security, D. The increase the size of broadcast domains while decreasing the number of the broadcast domains. E. The increase the number of broadcast domains while decreasing the size of the broadcast domains. F. They simplify switch administration. Answer: B, C, E 3 Explanation : There are many motivations for using VLANs, including these: 1. To group users by department, or by groups that work together, instead of by physical location. (B) 2. To reduce overhead by limiting the size of each broadcast domain (E) 3. To enforce better security by keeping sensitive devices on a separate VLAN (C) 4. To separate specialized traffic from mainstream traffic -for example, putting IP telephones on a separate VLAN form user PCs. Question 5 What are some of the characteristics of a typical VLAN arrangement, found throughout a switched LAN? (select all that apply) A. VLANs logically divide a switch into multiple, independent switches at Layer 2. B. Trunk links can carry traffic for multiple VLANs. C. VLAN implementation significantly increases traffic due to added trunking information. D. A VLAN can span multiple switches. E. VLANs typically increase the number of switches needed F. VLANs typically decrease the number of switches needed Answer: A, B, D Explanation : VLANs give you the power of making virtual LAN networks to subdivide collision domains into smaller units of functionality, without being limited by physical location. A is correct because that is the exact function of a VLAN. B is correct because trunk links are used to carry traffic for multiple VLANs. D is correct because a VLAN can and often does span across multiple switches. VTP makes this possible. Incorrect Answers : C => Although trunking information does indeed add some level of overhead, the overall traffic overhead is greatly reduced though the use of VLANs. E, F => The number of total switches needed in a network is the result of the number of devices on the entire LAN that need to be connected. Whether VLANs are used or not will have little, if any, impact on the total number of switches needed in a LAN. 4 Question 6 How could a corporation benefit from using VLANs on their network? (select three answer choices.) A. VLANs allow access to network services based on department, not physical location. B. VLANs utilize packet filtering to enhance network security. C. VLANs provide a low-latency, high bandwidth internetworking alternative. D. VLANs provide a method of communication between IP addresses in large networks. E. VLANs establish segmented broadcast domains in switched networks. F. VLANs can greatly simplify adding, moving, or changing hosts on the network. Answer: A, E, F Explanation: VLANs establish broadcast domains in switched networks, so by virtue of having the option to create many efficient broadcast domains, congestion is reduced and network throughput is greatly enhanced. VLANs allow networks to be divided by department or resource needs, rather then by physical location. When people move departments, leave a department, or join a department, administration is easy and convenient with a few keystrokes. Incorrect Answers: B, D => These would be router functions at layer 3. Switches and VLANs operate at layer 2 of the OSI model. C => The use of VLANs may actually increase the latency in some cases, as traffic from one VLAN to the other will need to be routed. 5 Question 7 Two VLANs are configured to a switch: VLAN1 and VLAN2. Hosts connected to the VLAN1 can communicate with each other but are unable to communicate with hosts on VLAN2. What is needed to allow communication between hosts belonging to VLAN1 and VLAN2? A. A router with sub interfaces configured on the physical interface that is connected to the switch B. A router with an IP address on the physical interface that is connected to the switch C. A switch with a trunk link that is configured between the switches D. A switch with an access link that is configured between the switches E. None of the above Answer: A Question 8 You are working as a network manager at a corporation, when you get a call from the Sales Department. They're complaining that they're receiving network traffic broadcasts obsolete information from the Development Department. What can you do to contain the Development Department broadcast while still keeping it connected to the internet and the enterprise services of the corporation? (select all valid answer choices) A. Use half and full-duplex Ethernet on the Sales Department LAN B. Establish a VTP domain to minimize the obsolete traffic C. Change the switch IP address of the switch D. Create separate VLANs and subnets for the two departments and route between the two E. Provide greater bandwidth to the Sales Department LAN F. Place the Development Department on a separate subnet and route between networks Answer: D, F Explanation: In order to prevent the broadcast and link level multicast traffic separated between the departments, they need to be isolated at layer two. This can be accomplished in two ways. - The first is to create separate VLANs and place each department into a different one. 6 - The second method would be to separate the two departments into two completely different networks, and route between them. Incorrect Answers: A => Mixing the use of half and full duplex will make no difference to the number of broadcasts sent. B => Trunking is only useful in networks that already contain VLANs.