CompTIA Network Recertification Exam for Continuing Education
Question No: 141 – (Topic 5)
A network administrator has created a virtual machine in the cloud. The technician would like to connect to the server remotely using RDP. Which of the following default ports needs to be opened?
Answer: B Explanation:
RDP (Remote Desktop Protocol) is used for connecting to a remote Windows computer. When using RDP to connect to a remote Windows computer, you can view and control the desktop of the remote computer. RDP uses TCP port 3389.
Question No: 142 – (Topic 5)
Which of the following describes an area containing a rack that is used to connect
customer equipment to a service provider?
Answer: B Explanation:
MDFstands for Main Distribution Frame. A Main Distribution Frame is a commonly a long steel rack accessible from both sides. On one side of the rack is cabling that connects the service provider’s network. The other side of the rack is for the connections tothe customer’s equipment.
Question No: 143 – (Topic 5)
A network technician has just installed a TFTP server on the administrative segment of the network to store router and switch configurations. After a transfer attempt to the server is made, the process errors out. Which of the following is a cause of the error?
Only FTP can be used to copy configurations from switches
Anonymous users were not used to log into the TFTP server
An incorrect password was used and the account is now locked
Port 69 is blocked on a router between thenetwork segments
Answer: D Explanation:
The question states that the TFTP server is installed on the “administrative segment of the network”. This implies that the network has multiple segments (subnets) and TFTP server is on a different network segment to other computers.
For a computer on one subnet to connect to a computer on a different subnet, a router is required to route traffic between the two subnets. Routers often include firewalls so they can be configured to allow specific traffic to be routed between the subnets and block unwanted traffic.
TFTP uses UDP port 69. The most likely cause of the connection timeout error in the question is that the firewall has not been configured to allow traffic using UDP port 69.
Question No: 144 – (Topic 5)
Which of the following devices implements CSMA/CA virtually through the RTS/CTS protocols?
C. 802.11 AP
Answer: C Explanation:
802.11 AP is a Wireless Access Point used in a wireless network.
If two computers on a network send data frames at thesame time, a collision between the frames can occur. The frames are then discarded and the sending computers will attempt to send the data again.
Carrier sense multiple access with collision avoidance (CSMA/CA) is a protocol used in wireless networks wherecomputers connected to the wireless network attempt to avoid collisions by transmitting data only when the channel is sensed to be quot;idlequot;. Carrier Sense Multiple Access/Collision Detect (CSMA/CD) is unreliable in wireless networks because computers connected to the wireless network often cannot see each other so CSMA/CA is a better option for avoiding collisions.
Request to Send/Clear to Send (RTS/CTS) can also be used to mediate access to the wireless network. This goes some way to alleviating the problemof computers not being able to see each other because in a wireless network, the Wireless Access Point only issues a “Clear to Send” to one node at a time.
With RTS/CTS, a Request to Send (RTS) packet is sent by the sending computer, and a Clear to Send(CTS) packet is sent by the intended receiver. This will alert all computers within range of the sender, receiver or both, to not transmit for the duration of the transmission. This is known as the IEEE 802.11 RTS/CTS exchange.
Question No: 145 – (Topic 5)
When troubleshooting a network problem, browsing through the log of a switch, it is discovered that multiple frames contain errors. In which of the following layers does the problem reside? (Select TWO).
Answer: A,E Explanation:
Layer 2 of the OSI reference model is the data-link layer. Components of the data-linklayer include frame-format, Media Access Control (MAC) addressing, protocol identification and error detection.
When data is being sent, it is split into protocol data units (PDUs) as it passes through the layers of the OSI model. The PDUs have different names as they are passed through the layers of the OSI model. In layer 2, the PDU is called a ‘Frame’.
The most common protocol specified in the data-link layer is Ethernet and the most common network component in the data-link layer is a network switch.
Inthis question, problems are discovered with Ethernet frames by examining the logs in a network switch. Therefore, for this question, we are working in Layer 2, the data-link layer.
Question No: 146 – (Topic 5)
A network technician is attempting to locate a switch connected to the fourth floor west side of the building. Which of the following will allow quick identification of the switch, when looking at a logical diagram?
Patch panel labeling
The building in this question has several floors and the floors are large enough to be identified by area such as ‘west side’ etc. It is likely that a logical diagram of the network in such a building would be quite complicated and the network is likely to have several switches.
A naming convention is a standard for naming items, in this case, networking components. When it comes to naming switches, using names like Switch1, Switch2 etc. for example won’t help when you need to know where the switches are located.
In a building with multiple floors with each floor large enough to be defined by area names, you could a naming convention like SW1-FL4-WS where SW1 identifies the item as a Switch with the number 1, FL4 identifiesthe location as Floor 4 and WS further identifies the location as West Side. Using this convention, switch number 2 on the third floor east side would be named SW2-FL3-ES.
Question No: 147 – (Topic 5)
Which of the following PDUs is used by a connectionless protocol?
Answer: D Explanation:
UDP is a connectionless transport protocol that operates in the transport layer of the OSI model. UDP stands for User Datagram Protocol. PDUs (Protocol Data Units) used by UDP are known as Datagrams.
Question No: 148 – (Topic 5)
A technician has prolonged contact with a thermal compound. Which of the following resources should be consulted?
Answer: B Explanation:
MSDS stands forMaterial Safety Data Sheet. An MSDS is a health and safety document that contains information on the potential hazards of working with a chemical product and how to work safely with the chemical product.
In this question, the thermal compound is a chemical product so the MSDS will provide information about the effects of prolonged contact with the thermal compound.
Question No: 149 – (Topic 5)
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 MACSRC IPDST MACDST IP 00:1D:1F:AB:10:7D192.168.1.10:200015:BE:9F:AB:10:1D192.168.1.14:1200
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?
Answer: A Explanation:
If we look at the Source Mac column, we can see two different MAC addresses. Everynetwork 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 twocomputers, 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.
Question No: 150 – (Topic 5)
Which of the following is the main difference between TCP and UDP?
TCP data flows in two directions, while UDP data flows from server to client.
The TCP header implements flags, while the UDP header does not.
The TCP header implements checksum, while the UDP header does not.
TCP connections can be secured by stateful firewalls, while UDP connections cannot.
Answer: B Explanation:
Transmission Control Protocol (TCP) is a connection-oriented transport protocol. Connection-oriented transport protocols provide reliable transport. When a computer wants to send data to another computer, TCP will first establish a connection between the two computers. When a sending computer sends data segments, the receiving computer acknowledges receipt of thesegments. If the receiving computerdoes not receive an expected segment, the sending computer will send it again.
User Datagram Protocol (UDP) is a connectionless transport protocol. Connectionless transport protocols provide unreliable transport. With UDP, there is no connection establishment between the sending and receiving computers. If a data segment is lost in transit, the sending computer will not know about it so it will not resend the segment.
TCP uses control messages to manage the process of contact and communication. TCP uses a set of control flags in the TCP header to indicate whether a segment is being used for control purposes or just to carry data.
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