ChApTEr 12 : Network Troubleshooting Methodology 626 What is the difference between TCP and UDP if they both operate Q: at the transport layer? Although both TCP and UDP are transport layer protocols and A: provide the same basic function, TCP is a connection-oriented protocol, which means a session is established before data is transmitted, and acknowledgments are sent back to the send- ing computer to verify that the data did arrive and was accurate and complete. UDP is connectionless; no session or one-to-one connection is established prior to data transmission. This makes UDP the faster of the two, while TCP is the more reliable. SElF TEST You are a network consultant specializing in supporting Small 1. Office Home Office (SOHO) networks. One of your clients maintains an office consisting of three workstations configured in a peer-to-peer workgroup. This office does not have a server computer at this time. One of the workstations, \\OFFICE1, has an IP address of 192.168.1.100 and has a file share that the other three workstations are able to access using the follow- ing syntax: \\OFFICE1\share. Your client has called you in to troubleshoot a new workstation that they have recently installed that is unable to access this share. When you arrive on-site, you find that the workstation is able to ping OFFICE1 by its IP address, but not by its NetBIOS name. What is the best way for you to allow the new workstation to access the file share located on OFFICE1? A. Upgrade OFFICE1 to Windows 2003 server and configure the WINS Server service. B. Add an entry to the lmhosts file on the new workstation. C. Add an entry to the findhosts file on the new workstation. D. Upgrade OFFICE1 to Windows 2003 server and configure the DNS service. You are troubleshooting network connectivity issues on a network 2. that is running Windows servers and clients. Users are reporting that they are unable to send e-mail, though they have been receiving messages from external users without a problem. During your troubleshooting, you see the configuration item on the Windows server that is shown in Figure 12.8. Based on this information, how can you correct the issue that this office is reporting? Self Test 627 A. Install and configure the POP3 service. B. Change the startup type of the SNMP Trap Service to Automatic. C. Start the SMTP service. D. Start the Routing and Remote Access Service. FIGurE 12.8 Services Console. You are a network consultant and have been called in to 3. troubleshoot a connectivity issue on a UNIX network. From the client’s UNIX workstations, which of the following utilities can you use to perform network troubleshooting? (Select all that apply.) A. ping B. tracert C. pathping D. traceroute E. nslookup F. dig 4. You are the network administrator for a network that employs a Windows 2003 server and 30 Windows XP Professional workstations. The Windows 2003 server runs the DHCP service to provide TCP/IP configuration information to the Windows XP clients. You receive a call from one of your users stating that he ChApTEr 12 : Network Troubleshooting Methodology 628 is unable to browse any internal network resources or Internet Web sites. Other users on the same subnet are able to browse without difficulty. You run the ipconfig command on the problem workstation and see the following output: Windows IP Configuration Host Name . . . . . . . . . . . . : IBM-A38375FF22E Primary Dns Suffix . . . . . . . : Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No Ethernet adapter Wireless Network Connection: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Intel(R) PRO/Wireless 2200BG Network Connection Physical Address. . . . . . . . . : 00-1E-25-1A-D3-5A Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : 169.254.1.96 Subnet Mask . . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . . : DHCP Server . . . . . . . . . . . : DNS Servers . . . . . . . . . . . : Lease Obtained. . . . . . . . . . : Tuesday, March 29, 2005 1:00:10 PM Lease Expires . . . . . . . . . . : Wednesday, March 30, 2005 1:00:10 PM Based on this output, why is this workstation unable to browse any network resources? A. The default gateway is unavailable. B. The workstation could not contact a DHCP server. C. The workstation is configured with the incorrect default gateway. D. The workstation’s DHCP lease has expired. Self Test 629 You are the network administrator for a sales office. Until now, 5. this has been a small peer-to-peer network consisting of five Windows XP workstations using lmhosts files on each workstation to perform name resolution. The sales force has recently expanded significantly, requiring you to purchase a Windows Server 2003 server and 15 additional workstations. You have encountered numerous troubleshooting situations where a workstation’s lmhosts file was missing or out of date, preventing name resolution from taking place. How can you improve the name resolution process for your network? A. Install the DNS service on the Windows 2003 server. B. Install the WINS service on the Windows 2003 server. C. Install the DHCP service on the Windows 2003 server. D. Install the DNS service on each Windows XP workstation. You are the network administrator for a large pharmaceutical compa-6. ny that has more than 1,000 workstations. To simplify TCP/IP con- figuration for these numerous clients, you installed a DHCP server over a year ago to automatically configure your clients with an IP address, as well as the following common configuration information: A. Subnet Mask: 255.255.0.0 B. Default Gateway: 172.16.0.1 C. DNS Servers: 172.16.0.100 D. 172.16.0.101 As part of a recent network redesign, you had to change the default gate- way used by your clients to a different IP address: 172.16.1.1. You made the necessary change on the DHCP server, and most of your clients were updated automatically. After you make this change, you receive a call from one user who no longer is able to browse the Internet. You examine the TCP/IP configuration of her LAN connection (Figure 12.9). How can you configure this workstation with the correct default gateway information? (Each choice represents a complete solution. Choose two.) A. Delete the manually configured information and select Obtain an IP address automatically. B. Run ipconfig /renew from the command prompt. C. Manually update the IP address of the default gateway. D. Run ipconfig /release from the command prompt. ChApTEr 12 : Network Troubleshooting Methodology 630 You are the administrator for the network shown in the Figure 12.10. 7. Based on the information in this figure, which computer is config- ured incorrectly? A. Computer1 B. Computer2 C. Computer3 FIGurE 12.9 TCP/IP Properties. Self Test 631 D. Computer4 E. Computer5 F. Computer6 G. Computer7 H. Computer8 FIGurE 12.10 Sample network architecture. You are the network administrator for the network shown in 8. Figure 12.11. You have recently purchased a new Windows XP workstation called Computer9 that you now need to add to Subnet C. Which of the following would be a valid IP address that would allow Computer9 to access resources on all four subnets? A. 192.168.3.155 B. 192.168.3.1 C. 192.168.3.0 D. 192.168.3.255 ChApTEr 12 : Network Troubleshooting Methodology 632 You are the administrator for the network shown in Figure 12.12. 9. You receive a help desk call from the user of Computer8, stating that she cannot browse the Internet or access a shared folder located on Computer5. Upon investigating the issue, you find that Computer7 is able to access the Internet and other shared resources, but Computer8 cannot ping any other hosts on the network. Based on this information, which of the following are likely points of failure that you should investigate? (Each selection represents a complete choice. Select all that apply.) A. The NIC installed in Computer8 B. The network cable attaching Computer8 to the network C. The NIC installed in Router A attached to Subnet B D. The TCP/IP configuration of Computer7 FIGurE 12.11 Sample network architecture. Self Test 633 FIGurE 12.12 Sample network architecture. You are the administrator of the network shown in Figure 12.13. The 10. firewall in the exhibit was installed by an outside consultant a few weeks ago. Once a month, one of your company’s employees needs to access the FTP site of one of your company’s business partners, ftp.airplanes.com, to download large PDF files containing prod- uct marketing information. You receive a help desk call from this employee, stating that he is now unable to access this FTP site. The last time he performed this task was before the firewall was installed, and he says that it worked fine then. You are able to ping the ftp. airplanes.com DNS name, and you can access www.airplanes.com, which is located on the same physical machine. What is the best way to restore this employee’s access to the ftp.airplanes.com FTP site? A. Configure a firewall rule allowing traffic to TCP ports 20 and 21. B. Configure a firewall rule allowing traffic to TCP ports 25 and 110. C. Configure a firewall rule allowing all TCP traffic to this employee’s workstation. D. Configure a firewall rule allowing traffic to TCP ports 80 and 443. ChApTEr 12 : Network Troubleshooting Methodology 634 You are the network administrator for a medium-sized law firm. 11. You have recently deployed a WAP for use by your internal support staff and attorneys. You have been charged with ensuring that only legitimate users of your company network will be able to access these WAPs. What are some steps you can take to enable network connectivity to your WAP so that only legitimate users will be able to obtain access? (Each choice represents a complete answer. Choose all that apply.) A. Enable MAC address filtering. B. Enable the default SSID broadcast. C. Enable WEP or WPA encryption. D. Enable the DHCP server on the WAP. FIGurE 12.13 Sample network architecture. Self Test 635 You are the administrator of the network shown in Figure 12.14. 12. You receive a call from the users of Computer5 and Computer6, stating that they cannot access any resources on the Internet. No other users on the network are reporting outages. Based on this diagram, what is most likely causing this connectivity issue? A. The network cable attaching Computer5 to the network B. The 192.168.1.1 interface on Router A C. The 192.168.4.1 interface on Router B D. The 192.168.5.1 interface on Router A FIGurE 12.14 Sample network architecture. . Mask: 255.255.0.0 B. Default Gateway: 172.16.0.1 C. DNS Servers: 172.16.0.100 D. 172.16.0.101 As part of a recent network redesign, you had to change the default gate- way used by your clients. one of your company’s employees needs to access the FTP site of one of your company’s business partners, ftp.airplanes.com, to download large PDF files containing prod- uct marketing information.