CompTIA Network+ Question C-69

A network technician has detected a personal computer that has been physically connected to the corporate network. Which of the following commands would the network technician use to locate this unauthorized computer and determine the interface it is connected to?

A. nbtstat –a
B. show mac address-table
C. show interface status
D. show ip access-list
E. nslookup hostname

Correct Answer: B

Explanation:
The show mac address-table command is used to view the ageing timer, and also the unicast and multicast MAC addresses stored in the MAC address table by the switch. Furthermore, you can view all of the addresses in the table or only the addresses learned or specified on a particular port or VLAN.

CompTIA Network+ Question C-68

A technician needs to set aside addresses in a DHCP pool so that certain servers always receive the same address. Which of the following should be configured?

A. Leases
B. Helper addresses
C. Scopes
D. Reservations

Correct Answer: D

Explanation:
A reservation is used in DHCP to ensure that a computer always receives the same IP address. To create a reservation, you need to know the hardware MAC address of the network interface card that should receive the IP address.
For example, if Server1 has MAC address of 00:A1:FB:12:45:4C and that computer should always get 192.168.0.7 as its IP address, you can map the MAC address of Server1 with the IP address to configure reservation.

CompTIA Network+ Question C-55

A wireless network technician for a local retail store is installing encrypted access points within the store for real-time inventory verification, as well as remote price checking capabilities, while employees are away from the registers. The store is in a fully occupied strip mall that has multiple neighbors allowing guest access to the wireless networks. There are a finite known number of approved handheld devices needing to access the store’s wireless network. Which of the following is the BEST security method to implement on the access points?

A. Port forwarding
B. MAC filtering
C. TLS/TTLS
D. IP ACL

Correct Answer: B

Explanation:
MAC filtering allows traffic to be permitted or denied based on a device’s MAC address. We make a MAC filtering which contains the MAC addresses of all approved devices that need to access the wireless network. This ensures that only approved devices are given access to the network.

CompTIA Network+ Question B-78

Which of the following would be the result of a user physically unplugging a VoIP phone and connecting it into another interface with switch port security enabled as the default setting?

A. The VoIP phone would request a new phone number from the unified communications server.
B. The VoIP phone would cause the switch interface, that the user plugged into, to shutdown.
C. The VoIP phone would be able to receive incoming calls but will not be able to make outgoing calls.
D. The VoIP phone would request a different configuration from the unified communications server.

Correct Answer: B

Explanation:
Without configuring any other specific parameters, the switchport security feature will only permit one MAC address to be learned per switchport (dynamically) and use the shutdown violation mode; this means that if a second MAC address is seen on the switchport the port will be shutdown and put into the err-disabled state.

CompTIA Network+ Question B-1

A network administrator is using a packet analyzer to determine an issue on the local LAN. Two separate computers are showing an error message on the screen and are unable to communicate with other computers in the same lab. The network administrator looks at the following output:

SRC MAC SRC IP DST MAC DST IP
00:1D:1F:AB:10:7D192.168.1.10:200015:BE:9F:AB:10:1D192.168.1.14:1200
05:DD:1F:AB:10:27192.168.1.10:100022:C7:2F:AB:10:A2192.168.1.15:1300

Given that all the computers in the lab are directly connected to the same switch, and are not using any virtualization technology, at which of the following layers of the OSI model is the problem occurring?

A. Network
B. Application
C. Data link
D. Transport

Correct Answer: A

Explanation:
If we look at the Source Mac column, we can see two different MAC addresses. Every network interface card has a unique MAC address. These are the network cards in the two separate computers.
If we look in the Source IP column, we can see that the two network cards have been assigned the same IP address (192.168.1.10). This is the problem in this question. The error message on the screens will be saying that “An IP conflict exists”. Every network card connected to the network needs to be configured with a different IP address.
As the problem is with the IP address configuration of the two computers, we know that the problem is occurring at the Network layer (layer 3) of the OSI model. The network layer is responsible for Internet Protocol (IP) addressing and routing.

CompTIA Network+ Question A-79

A network topology that utilizes a central device with point-to-point connections to all other devices is which of the following?

A. Star
B. Ring
C. Mesh
D. Bus

Correct Answer: A

Explanation:
A Star network is the most common network in use today. Ethernet networks with computers connected to a switch (or a less commonly a hub) form a star network. The switch forms the central component of the star. All network devices connect to the switch. A network switch has a MAC address table which it populates with the MAC address of every device connected to the switch. When the switch receives data on one of its ports from a computer, it looks in the MAC address table to discover which port the destination computer is connected to. The switch then unicasts the data out through the port that the destination computer is connected to.

CompTIA Network+ Question A-43

After connecting a workstation directly to a small business firewall, a network administrator is trying to manage it via HTTPS without losing its stored configuration. The only two pieces of information that the network administrator knows about the firewall are the management interface MAC address, which is 01:4a:d1:fa:b1:0e, and the administrator’s password. Which of the following will allow the administrator to log onto the firewall via HTTPS if the management’s IP address is unknown and the administrator’s workstation IP address is 192.168.0.10/23?

A. Use the reset button on the back of the firewall to restore it to its factory default, and then log onto
B. Run the following command on the administrator’s workstation: arp –s 192.168.1.200 01:4a:d1:fa:b1:0e
C. Use an SNMP tool to query the firewall properties and determine the correct management IP address
D. Use a crossover cable to connect to the console port and reconfigure the firewall management IP to 192.168.0.1

Correct Answer: B

Explanation:
Address Resolution Protocol (ARP) is used to resolve IP addresses to MAC addresses. The arp –s command adds a static permanent address to the ARP cache. This will allow the administrator to access the firewall.

CompTIA A+ Core 2 Question J-79

Which of the following should a technician implement to prevent external contractors from physically plugging devices into the company’s network jacks unless such jacks are designated for guest use?

A. Disable DHCP and assign a static IP address to each network device physically connected to the network.
B. Enable MAC address filtering across all network jacks and record the MAC address of guest devices.
C. Disable all switch ports when they are not utilized and enable them on an as needed basis.
D. Place guest network jacks in public areas and all other jacks in secure areas as needed.

Correct Answer: C

CompTIA A+ Core 2 Question G-94

A user attempts to remote into their machine at night but cannot connect. The user believes that someone is unplugging their computer from the network at night and plugging in a personal machine. Which of the following security measures would BEST prevent this behavior from continuing?

A. Limit the port to a specific MAC address.
B. Set the port to only activate during business hours.
C. Disable DHCP on the network router.
D. Deactivate the port that is being used from the switch.

Correct Answer: A