20.7.3 Module 20 – Troubleshoot Common Network Problems Quiz Answers
1. The home computer of a user is working properly. However, the user cannot access the Internet. The Internet connection is provided through a cable company. The user cannot identify the cause of the problem. Who should the user contact for further help?
- the help line of the cable company
- the help line of the computer manufacturer
- the support web site of the computer vendor
- the operating system vendor
Explanation: Assuming the computer was working properly before, the most possible cause of the problem is the Internet connection provided by the cable company. Computer vendors and manufacturers cannot help because the computer is working properly.
2. A network technician enters the command ipconfig /release followed by ipconfig /renew in order to ensure that the DHCP IP configuration on a workstation is updated. However, the workstation does not receive a valid IP configuration for the network. Which two problems may exist on the network? (Choose two.)
- There is no network connectivity to the DHCP server.
- The ipconfig /all command must be issued to restore all IP configurations.
- The DHCP lease time is misconfigured.
- There is a DHCP server issue.
- The gateway router address needs to be updated.
Explanation: The command ipconfig /release will release the current DHCP binding. Ipconfig /renew will request fresh configuration information from the DHCP server. After these two commands are issued, if the workstation is unable to obtain a valid IP configuration from the DHCP server, it could be that there is no network connectivity or the DHCP server is not operational.
3. Refer to the exhibit. The command output is from a wireless DHCP host connected to a Linksys integrated router. What can be determined from the output?
- The connection to the SSID needs to be verified.
- A new wireless NIC needs to be installed.
- There is a DNS problem.
- The DHCP configuration needs to be checked.
- An incorrect cable is being used between the host and the router.
Explanation: The default gateway IP address must be in the same network as the host in order for the host and router to communicate with each other. Because this is a DHCP client, the IP configuration is provided by the DHCP. Thus the DHCP configuration should be checked and corrected.
4. A customer called the cable company to report that the Internet connection is unstable. After trying several configuration changes, the technician decided to send the customer a new cable modem to try. What troubleshooting technique does this represent?
- bottom-up
- divide-and-conquer
- substitution
- top-down
Explanation: During troubleshooting, when the problem seems to be caused by a defective hardware, one approach is to replace the suspected hardware with a known good one. While not necessarily locating the problem, this technique can save time and quickly restore system functionality.
5. A small office uses a wireless router to connect to a cable modem for internet access. The network administrator receives a call that one office computer cannot access external websites. The first troubleshooting step that the network administrator performs is to ping the wireless router from the office computer. Which troubleshooting technique does this represent?
- divide-and-conquer
- bottom-up
- top-down
- substitution
Explanation: A ping to the wireless router can verify Layer 3 connectivity. As a troubleshooting method, this is the divide-and-conquer approach.
6. A network administrator can successfully ping the server at www.cisco.com, but cannot ping the company web server located at an ISP in another city. Which tool or command would help identify the specific router where the packet was lost or delayed?
- netstat
- traceroute
- telnet
- ipconfig
Explanation: The traceroute command provides connectivity information about the path a packet takes to reach the destination and about every router (hop) along the way. It also indicates how long a packet takes to get from the source to each hop and back.
7. Which command would a technician use to display network connections on a host computer?
- nslookup
- netstat
- ipconfig
- tracert
Explanation: The netstat command is a network utility that can be used to display active TCP connections that are open and running on a networked host.
8. Which three items should be documented after troubleshooting an internal web server crash? (Choose three.)
- the dialogue with the user
- when the problem occurred
- the configuration of all networking devices on the LAN at the time of the crash
- steps that were performed that failed to identify the cause of the problem
- the configuration of all hosts on the LAN at the time of the crash
- steps that were performed to identify the cause of the problem
Explanation: Proper documentation is a very important step in troubleshooting. The proper documentation can help troubleshoot the same or similar problems in the future. The documentation should include as much information as possible about the following:
- the problem encountered
- steps taken to determine the cause of the problem
- steps to correct the problem and ensure that it will not reoccur
9. A user calls the help desk to report a workstation problem. Which three questions would produce the most helpful information for troubleshooting? (Choose three.)
- If you received an error message, what was it?
- Do you have the warranty for your workstation?
- Have you performed a backup recently?
- What operating system version is running on your workstation?
- What changes have you made to your workstation?
- Have you used a network monitoring tool on your workstation?
Explanation: In troubleshooting, the first step is to gather information related to the problem. One way to gather information is to ask questions of the individual who reported the problem as well as any other affected users. Questions should include end user experiences, observed symptoms, error messages, and information about recent configuration changes to devices or applications.
10. What are two common causes of a physical layer network connectivity problem? (Choose two.)
- a faulty Ethernet cable
- an Ethernet cable plugged into a wrong port
- an incorrect default gateway
- a monitor unplugged
- an unassigned IP address
Explanation: An Ethernet cable plugged into a wrong port and a faulty Ethernet cable are two possible causes for physical network connectivity issues. An incorrect default gateway configuration and a lack of an IP address will cause logical connectivity issues.
11. Refer to the exhibit. A web designer calls to report that the web server web-s1.cisco.com is not reachable through a web browser. The technician uses command line utilities to verify the problem and to begin the troubleshooting process. Which two things can be determined about the problem? (Choose two.)
- A router is down between the source host and the server web-s1.cisco.com.
- DNS cannot resolve the IP address for the server web-s1.cisco.com.
- The web server at 192.168.0.10 is reachable from the source host.
- There is a problem with the web server software on web-s1.cisco.com.
- The default gateway between the source host and the server at 192.168.0.10 is down.
Explanation: The successful result of the ping to the IP address indicates that the network is operational and the web server is online. However, the fact that the ping to the domain name of the server fails indicates there is a DNS issue, namely that the host cannot resolve the domain name to its associated IP address.
12. Which step should be taken next once a problem is resolved during a troubleshooting process?
- Update the documentation.
- Escalate the problem.
- Run remote access software.
- Consult an FAQ.
Explanation: Proper documentation can help troubleshoot the same or similar problems in the future. Proper documentation should include the type of error encountered, the steps taken to determine the cause of the problem, and the steps taken to correct the problem.