Unit 6 Test Review

Users in a recently installed wireless network are complaining of slow data transfer and frequent loss of connectivity. The technician checks that the wireless security is correctly implemented, and there is no evidence of unauthorized users on the network. Which two problems might the technician suspect?

• There is interference from outside sources.

• The wireless signal is too weak.

• The DHCP server is faulty.

Answer explanation

• Normally, the closer a wireless NIC is to an access point, the faster the connectivity. This problem does not require the network password to be reissued. The combination of the low bandwidth and the intermittent connectivity is pointing towards a weak signal or interference from outside sources.

A wired network is undergoing several changes that could leave it vulnerable to connection by unauthorized devices while the work is in progress. Which two temporary measures would enable the authorized devices to continue to have network access but prevent unauthorized devices from connecting?

• Disable DHCP.

• Assign static IP addresses to the authorized devices.

• • Disable DNS.

• • Disable SSID broadcast.

Answer explanation

• Disabling DHCP and assigning static IP addresses only to authorized devices will prevent unauthorized devices from automatically obtaining IP address information. Without the correct IP address information, the unauthorized devices will not be able to communicate over the network. Disabling DNS will result in all connected devices no longer automatically being able to communicate with network resources by name (IP addresses would have to be used.), but will not prevent unauthorized devices from connecting and enabling potentially malicious access from occurring. Subnetting the network will change the range of IP addresses used but not prevent unauthorized network access. Disabling SSID broadcasts is only applicable to wireless networks, not wired networks.

What two default wireless router settings can affect network security?

• The SSID is broadcast.

• A well-known administrator password is set.

• • MAC address filtering is enabled.

• • WEP encryption is enabled.

Answer explanation

• Default settings on wireless routers often include broadcasting the SSID and using a well-known administrative password. Both of these pose a security risk to wireless networks. WEP encryption and MAC address filtering are not set by default. The automatic selection of the wireless channel poses no security risks.

A network technician is checking a computer to see if the DHCP client is working correctly. The technician issues the ipconfig /all command. Which two parameters should the technician review?

• default gateway

• subnet mask

• host name

Answer explanation

• A DHCP server can provide several parameters such as IP address, subnet mask, default gateway, and other optional parameters. The host name, media state, and description are present even if a DHCP server is not found.

A technician is troubleshooting a problem where the user claims access to the Internet is not working, but there was access to the Internet the day before. Upon investigation, the technician determines that the user cannot access the network printer in the office either. The network printer is on the same network as the computer. The computer has 169.254.100.88 assigned as an IP address. What is the most likely problem?

• • The computer cannot communicate with a DHCP server.

• • The router that connects this network to other networks is down

• • The router that connects this network to other networks is down

• • The IP default gateway on the computer is incorrect.

Answer explanation

• In a network employing dynamic IP addressing, if a computer cannot communicate with the DHCP server to obtain an IP address, the Windows operating system automatically assigns a link-local IP, which is in the range of 169.254.0.0 to 169.254.255.255. In this case, the computer can only communicate with computers connected to the same network within this IP address range.

A user can print to a printer that is on the same network, but the traffic of the user cannot reach the Internet. What is a possible cause of the problem?

• • The PC default gateway address is missing or incorrect.

  
  

• • The NIC on the PC is faulty.
    

  
  

Answer explanation

• In a network employing dynamic IP addressing, if a computer cannot communicate with the DHCP server to obtain an IP address, the Windows operating system automatically assigns a link-local IP, which is in the range of 169.254.0.0 to 169.254.255.255. In this case, the computer can only communicate with computers connected to the same network within this IP address range.

Port triggering has been configured on a wireless router. Port 25 has been defined as the trigger port and port 113 as an open port. What effect does this have on network traffic?

• All traffic that is sent out port 25 will open port 113 to allow inbound traffic into the internal network through port 113.
  

• • Any traffic that comes into port 25 allows outgoing port 113 to be used.

  
  

Answer explanation

• Port triggering is used to allow inbound traffic through the firewall based on outbound traffic. The trigger occurs when an application makes use of a specific port on the internal network. An external port on the firewall is then opened. This allows for temporary passage of traffic through inbound ports to a specific device.

A PC is not able to connect to a wired network. Pinging the loopback address is successful, but the gateway cannot be reached. On the network switch all the interface lights are on, except for the interface connected to the PC. The LED on the network card is off. What is the most likely cause of this problem?

• • The gateway needs to be fixed.

  
  

• • The network cable is faulty.

  
  

• • The network switch is faulty.

  
  

• The PC has an incorrect IP address for the DNS server.
  

Answer explanation

• The network card is working if the loopback address can be pinged. The LED on the network card being off points towards a faulty cable or a bad connection.

The current IP configuration of a small company is done manually and is time-consuming. Because of increased network growth, a technician needs a simpler way for IP configuration of workstations. Which service would simplify the workstation IP configuration task?

Answer explanation

• In networks with more than a few hosts, DHCP simplifies the addressing process. A DHCP server automatically assigns host IP addresses.

A technician troubleshooting a network problem has used CLI commands to determine that a computer has not been allocated a correct IP address from the DHCP server. Which command can the technician use to solve this problem?