Apply Your Knowledge
Exercises
3.1 Determining MAC Addresses for Network Cards
This chapter identifies the characteristics and functions of network devices. In an ideal world, this project would require hands-on experience with these devices, but this is not an ideal world, and access to this equipment is not always easy. Therefore, we will include two exercises that you might be required to perform if such devices are used on your network.
This project assumes that you are using Windows 2000.
Estimated time: 20 minutes
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Open a command window by selecting Start, Run. In the command box, type command and then click OK.
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At the command prompt, type ipconfig/all. The MAC address of your NIC is displayed in the Physical Address line.
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Open a Web browser and go to the following Web site: http://standards.ieee.org/regauth/oui/oui.txt.
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Using the Find functionality in your Web browser, locate the entry that corresponds with the address of your NIC. Is the manufacturer of your NIC the company you expected it to be? Some NIC manufacturers re-brand cards manufactured by another company. For that reason, the MAC address may correspond to a manufacturer that is different from the brand name of the card.
3.2 Using the tracert Utility to View the Path to an Internet Destination
One of the tools network administrators have at their disposal is the tracert utility. tracert allows you to see the hops a network packet takes to get to its destination. At each point along the way, the packet gives information about the route it is taking, along with details of the routers it crosses. More information on the tracert utility is provided in Chapter 13, "Troubleshooting Connectivity."
Firewalls
If you are using a system that is protected by a firewall system, this exercise might not work because firewalls are commonly configured to block tracert traffic.
In this exercise, you will use the tracert utility to view the path to an Internet destination. This project assumes that you are using Windows 2000.
Estimated time: 5 minutes
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Open a command window by selecting Start, Run. In the command box, type cmd.exe and then click OK.
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At the command prompt, type tracert http://www.comptia.org. The route to the CompTIA Web server is displayed.
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How many hops are you from the destination?
Exam Questions
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You have configured a 100Mbps network connection between your computer and the switch as half-duplex. What will be the maximum speed of the connection?
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50Mbps
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100Mbps
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100MBps
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200Mbps
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You want to create a larger network by connecting two switches together. One of the switches has a port that can be switched from MDI to MDI-X as needed. The other switch doesn't have such a port or a dedicated uplink port. Which type of cable should you use, and how should you configure the switchable port to create the larger network?
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Use a straight-through cable and set the port to MDI
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Use a crossover cable and set the port to MDI-X
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Use a straight-through cable and set the port to MDI-X
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Use a crossover cable and set the port to MDI
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Of the following, which represents a valid MAC address?
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00:D0:59:09:07:51
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000:D00:599:099:071:512
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00:D0:59:09:07:51:C4:56
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00:H0:59:09:07:51
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A bridge makes forwarding decisions based on what information?
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IP address
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MAC address
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Binary address
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Frame address
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What information does a switch use to determine the port to which data should be sent?
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The IP address of the connected device
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The priority of the connected device
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The MAC address of the connected device
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The Ethernet address of the connected device
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Which of the following is a link-state routing protocol used on TCP/IP networks?
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RIP
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ARP
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OSPF
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NLSP
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On a Windows 2000 system, what command would you use to view the MAC address?
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ifconfig -a
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ipconfig /all
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ipconfig
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config /all
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What is the purpose of the uplink port on a hub or switch?
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It allows for satellite connections.
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It allows hubs or switches to be connected together.
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It allows computers to connect to the device.
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It provides a spare port, which can be used if another port fails.
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By what method does a router determine the destination address for a packet?
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It looks at the MAC address of the sender.
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It looks for the MAC address of the destination.
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It looks for the software-configured network address for the destination.
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It looks at the FCS field of the packet.
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Which of the following statements best describes split horizon?
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Routes are advertised back on the interface from which they were learned, with a metric of 16.
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Routes are advertised back on the interface from which they were learned, with a metric of 0.
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Routes are not advertised back on the interface from which they were learned.
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Routes are advertised back on the interface from which they were learned, with a metric of 16, and on all other interfaces they are advertised back on the interface from which they were learned, with a metric of 0.
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In a network that uses distance-vector routing protocols, what information is included in the update that is sent out by each router?
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Details of the routers to which it is directly connected
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A map of the entire network, with hop counts valued from its current position
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Details of all the routers it knows about
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Details of its own configuration
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What is the difference between an active hub and a passive hub?
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An active hub has management capabilities.
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An active hub forwards the data only to the ports that need it.
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An active hub channels bandwidth to a given connection if the connection becomes too slow.
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An active hub regenerates the signal before forwarding it.
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What condition can arise if routers advertise a route back to the router from which it was learned?
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Count to infinity
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Road to nowhere
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Loop de loop
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Count to 16
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What term is used by routers to describe each step necessary to reach a destination?
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Hop
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Jump
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Skip
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Leap
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What is the maximum speed of a 16550 UART chip?
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64,000bps
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115,200bps
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430,800bps
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921,600bps
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What is the name of the bridging method used to segregate Ethernet networks?
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Source-route
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Invisible
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Cut-through
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Transparent
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Which of the following is a distance-vector routing protocol used on TCP/IP networks?
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ARP
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NLSP
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OSPF
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RIP
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A CSU/DSU is used in which of the following network configurations?
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When converting from a Token Ring network to an Ethernet network
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When converting a digital signal to an analog signal
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When converting from the digital signals used on a LAN to the digital signals used on a WAN
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When converting from the digital signal format used on a LAN to the analog signal format used on a WAN
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A router makes its forwarding decisions based on which of the following information?
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IP address
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ARP address
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Binary address
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Frame address
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You are tasked with upgrading a new NIC in the company file and print server. Which of the following should you determine before buying a replacement card? (Choose the three best answers.)
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Bus compatibility
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Network compatibility
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Hardware compatibility
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Cooling requirements
Answers to Exam Questions
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b. A half-duplex connection operates at the normal speed of the link. Thus, a 100Mbps network connection in a half-duplex configuration would operate at a maximum of 100Mbps. All the other answers are invalid. For more information, see the section "Working with Hubs and Switches," in this chapter.
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b. Because one of the switches does not have MDI capability, the switchable port should be set to MDI-X. Then, a crossover cable should be used to cancel out the crossing between the two devices. None of the other options would result in a successful connection. For more information, see the section "Working with Hubs and Switches," in this chapter.
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a. A MAC address comprises 6 bytes presented in a hexadecimal format. The letters A through F and numbers 0 through 9 are the only valid characters. Therefore, all the other answers provided are incorrect. For more information, see the section "Identifying MAC Addresses," in this chapter.
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b. Bridges make forwarding decisions based on the destination MAC address embedded in each packet. Routers use software addresses, such as IP addresses, to make forwarding decisions. Answers c and d are not valid. For more information, see the section "Bridges," in this chapter.
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c. A switch uses the MAC address of the connected device to determine the port to which data is forwarded. Routers use software addresses, such as IP addresses, to make forwarding decisions. Answer b is not valid. Although there are many addressing schemes used on networks, Ethernet address is not a valid term. Therefore, Answer d is incorrect. For more information, see the section "Switches," in this chapter.
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c. OSPF is a link-state routing protocol used on TCP/IP networks. RIP is a distance-vector routing protocol used on both TCP/IP and IPX/SPX networks, ARP is a component of the TCP/IP protocol suite. NLSP is a link-state routing protocol used on IPX/SPX networks. For more information, see the section "Routers," in this chapter.
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b. The ipconfig /all command shows a range of network-related information, including the MAC addresses of any installed NICs. None of the other answers are valid. For more information, see the section "Identifying MAC Addresses," in this chapter.
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b. The uplink port can be used to connect hubs and switches together, using a standard twisted-pair cable. All the other answers are invalid. For more information, see the section "Working with Hubs and Switches," in this chapter.
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c. Routers use the software-configured network address to make routing decisions. Bridges use MAC addresses to make decisions. Answer d is not valid. The FCS (that is, frame checksum) field is used for error detection. For more information, see the section "Routers," in this chapter.
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c. Split horizon is a routing algorithm which dictates that routes are not advertised back on the interface from which they were learned. Answer a describes the operation of the split horizon with poison reverse algorithm. None of the other answers are valid. For more information, see the section "Routers," in this chapter.
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c. In a network that uses distance-vector routing protocols, routers advertise details of the routers they know about. These updates are sent to all the neighbor routers. Answer a describes the actions on a link-state-based network. Answers b and d are invalid. For more information, see the section "Routers," in this chapter.
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d. An active hub regenerates the data signal before forwarding it to all connected devices. Active hubs come in both managed and unmanaged varieties. Answer b describes the action of a switch. Answer c is invalid. For more information, see the section "Hubs," in this chapter.
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a. A count to infinity occurs when two routers provide information on the same destination and so create a routing loop. All the other answers are invalid. For more information, see the section "Routers" in this chapter.
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a. Each step in the path between a router and its destination is called a hop. The other terms are not used in networking. For more information, see the section "Routers," in this chapter.
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b. A 16550 UART chip is capable of speeds up to 115,200bps. None of the other answers are valid. For more information, see the section "Modems," in this chapter.
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d. The bridging method used on Ethernet networks is called transparent because the other network devices are unaware of the existence of the bridge. Source-route bridges are used on Token Ring networks, invisible is not a type of bridge, and cut-through is a switching method, not a type of bridge. For more information, see the section "Bridges," in this chapter.
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d. RIP is a distance-vector routing protocol used on TCP/IP networks. ARP is a component of the TCP/IP protocol suite. NLSP is a link-state routing protocol used on IPX networks, and OSPF is a link-state routing protocol used on TCP/IP networks. For more information, see the section "Routers," in this chapter.
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c. CSUs/DSUs are used to convert the digital signals used on a LAN to the digital signals used on a WAN. The process described in Answer a would be performed by a gateway, and the process described in Answer b would be performed by a modem. Answer d is not valid because WANs commonly use digital signals. For more information, see the section "CSU/DSU," in this chapter.
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a. Routers make routing decisions based on the software-configured network address, which is protocol dependent. There is no such thing as an ARP address. Answers c and d are invalid. For more information, see the section "Routers," in this chapter.
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a, b, c. You should verify bus compatibility, network compatibility, and hardware compatibility before you buy a new NIC. You do not typically need to concern yourself with cooling requirements of a component. For more information, see the section "Network Interface Cards (NICs)," in this chapter.
Suggested Readings and Resources
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Sloan, Joseph D. Network Troubleshooting Tools (O'Reilly System Administration). O'Reilly & Associates, 2001.
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Habraken, Joe. Absolute Beginner's Guide to Networking, third edition. Que Publishing, 2001.
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Haugdahl, J. Scott. Network Analysis and Troubleshooting. Addison-Wesley, 2000.
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Cisco Systems, Inc. Internetworking Troubleshooting Handbook, second edition. Cisco Press, 2001.
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Computer networking products and information, http://www.alliedtelesyn.com.
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Computer networking device information, http://www.3com.com.
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"Computer Networking Tutorials and Advice," compnetworking.about.com.
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"TechEncyclopedia," http://www.techencyclopedia.com.
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"Networking Technology Information from Cisco," http://www.cisco.com/public/products_tech.shtml.
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"Network Cabling Help," http://www.datacottage.com.