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Answers to Exam Prep Questions

  1. Answers B, D, and E are correct. Create the VLANs, name them, and assign the ports. Answer A is incorrect; VTP does not create VLANs, it updates other switches that you have configured as part of the VTP domain with VLAN information. Answer C is incorrect; VLANs do not themselves have passwords, but the VTP system might. Answer F is incorrect; trunk links are only necessary to carry multiple-VLAN traffic between switches or routers. Access ports for hosts are assigned to a single VLAN each, which gives the host access to that VLAN.
  2. Answers B, C, E, G, and H are correct; these are all stated advantages of VLANs. Answer A is incorrect; VLANs complement the use of subnets. Answer D is incorrect; VLANs have nothing whatsoever to do with encryption. Answer F is wrong. VLANs do not eliminate broadcasts; they only constrain them.
  3. Answers A and D are correct; Trunking protocols label each frame with its originating VLAN number so traffic from multiple VLANs can be multiplexed across a trunk link. By default, traffic from all VLANs is permitted across a trunk. Answer B is incorrect; 802.1Q is a standardized trunking protocol that enables inter-vendor switch links. Answer C is false; trunks are a Layer 2 construct that carry traffic from multiple VLANs and their associated subnets; the trunk itself does not require a subnet of its own to function
  4. Answers B, C, and E are correct. A single VLAN should be associated with a single IP subnet; each VLAN is a separate broadcast domain, segmented by the Layer 2 function of the switch, and Router-on-a-Stick configuration creates a virtual gateway (sub-interface) for each VLAN/subnet. Answer A is wrong; each VLAN should have its own subnet. Answer D is wrong; VLANs do not segment collision domains.
  5. Answers D and G are correct; these are the two trunking protocols supported by Cisco. Answers A, B, C, E, and F are wrong: STP eliminates Layer 2 loops; HSRP provides redundant gateway functionality; VTP dynamically updates VLAN information; 802.1d is the IEEE specification for STP; and 802.11b is the IEEE specification for Wi-Fi.
  6. Answers A, C, E, and F are correct. The on mode, off mode, auto mode, and desirable mode are trunk port modes. Answers B, D, and G are incorrect; these other modes are not associated with trunking.
  7. Answers B and F are correct. These two commands make a port a trunk and force it to use multiple-vendor–compatible protocol. Answer A is incorrect; the command must be issued at the config-if prompt. Answers C, D, and E are incorrect because they are invalid commands.
  8. Answers B, D, and F are correct. Server, Client, and Transparent are VLAN Trunking Protocol switch modes. Answers A, C, and E are not valid VTP modes.
  9. Answers B, D, F, and G are correct. These elements are required to create a functioning VTP system between two switches. Answer A is incorrect; one switch should be the Server for the domain. Answer C is incorrect, VTY is the Telnet lines. Answer E is wrong; we need trunks between switches to make VTP work. Answer H is wrong; hold-down timers are part of a routing protocol, not VTP.
  10. Answer B is correct. VLANS have the effect of totally isolating hosts in different VLANs as if they were plugged in to different switches that are not connected. A, C, and D are incorrect; STP prevents Layer 2 loops, GigaStacking uses high-speed connections to make two or more switches appear as one management unit, and VTP dynamically propagates VLAN updates to other connected switches.
  11. Answer B is correct. STP prevents Layer 2 loops if redundant paths exist. Answers A, C, D, and E are incorrect; STP is not concerned with routing loops, IP addresses, routing in general, or VLAN administration.
  12. Answers A and F are correct. The Bridge ID is the Priority prepended to the MAC address of the switch. The switch with the lowest Bridge ID becomes the Root; therefore, the switch with the lowest Priority will always be the Root. Answers B, C, D, E, and G are incorrect; the winning Bridge ID and Priority will be the lowest. The speed of the switch has no bearing on whether it will be the root if left to default settings. The number of connections to other switches has no impact either.
  13. Answer D is correct. Convergence in STP means that all ports are either blocked to prevent loops or forwarding to allow data transmission. (However, if all ports are blocking, the system has not converged yet.) Answers A, B, and C are incorrect; all switches must run STP or run the risk of loops destabilizing the network.
  14. Answer E is correct. The Root Path Cost is the accumulated cost of all the links on the path to the Root. The Cost is calculated based on the bandwidth of the links. Answers A, B, C, and D are incorrect. You must add the STP cost of all the links on the path to the Root; cost has nothing to do with delay or hop count.
  15. Answer B is correct; Switch B will become the Root because it has the lowest Priority. Remember that even though A has a lower MAC, the Priority overrides this, and the switch with the lowest Priority will be the Root. Answers A, B, and C are incorrect.
  16. Answer D is correct. Because D has the lower Root Path Cost (at 19) than C (at 23), D will make its port the Designated Port—even though C has a lower Bridge ID. Answers A, B, and C are incorrect; the Designated ports must be connected to the ethernet segment, and the switch with the lowest Root Path Cost will host the DP. Only if there is a tie for Root Path Cost will Bridge ID become a deciding factor.
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