1.
If a node receives a frame and the calculated CRC does not match the CRC in the FCS, what action will the node take?
Correct Answer
A. Drop the frame
Explanation
If a node receives a frame and the calculated CRC does not match the CRC in the FCS, the node will drop the frame. This is because the CRC (Cyclic Redundancy Check) is used to detect errors in the frame during transmission. If the calculated CRC does not match the CRC in the FCS (Frame Check Sequence), it indicates that there is an error in the frame. Therefore, the node will discard the frame to prevent the transmission of corrupted data.
2.
What are the contents of the data field in a frame?
Correct Answer
B. The network layer PDU
Explanation
The correct answer is "The network layer PDU." In a frame, the data field contains the network layer Protocol Data Unit (PDU). The PDU includes the actual data that needs to be transmitted over the network. The data could be in the form of packets or segments, depending on the network layer protocol being used. The data field does not include the Layer 2 source address or the data directly from the application.
3.
Which of the following is a characteristic of contention-based MAC?
Correct Answer
B. Nodes compete for the use of the medium.
Explanation
Contention-based MAC is a protocol used on nonshared media where nodes compete for the use of the medium. In this type of MAC, multiple nodes attempt to transmit data simultaneously and collisions may occur if two or more nodes transmit at the same time. The nodes then compete for retransmission by employing algorithms like CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to avoid further collisions. This characteristic allows for efficient sharing of the medium among multiple nodes.
4.
Which of the following describes a virtual circuit?
Correct Answer
D. Establishes a logical connection between two network devices
Explanation
A virtual circuit is a communication path that is established between two network devices. It is a logical connection rather than a physical one. Unlike a physical circuit, a virtual circuit does not require a dedicated physical connection, but rather uses existing network infrastructure to create a logical connection. This allows for efficient use of resources and enables data to be transmitted between the devices in a reliable and efficient manner. Virtual circuits are commonly used in packet-switched networks, such as the internet, where data is divided into packets and routed through the network.
5.
Which of the following functions does the data link layer perform?
Correct Answer
C. Connects the network software to the network hardware
Explanation
The data link layer is responsible for connecting the network software to the network hardware. This means that it provides the necessary interface for the network software to communicate with the physical network hardware, such as Ethernet cards or Wi-Fi adapters. It ensures that the data being sent by the network software is properly formatted and transmitted over the physical network, and also handles error detection and correction. By performing this function, the data link layer establishes a reliable connection between the network software and the network hardware, enabling the transmission of data between hosts.
6.
Which of the following is true about the logical topology of a network?
Correct Answer
D. Influences the type of MAC used in the network
Explanation
The logical topology of a network refers to how the nodes in the network are connected. It determines the flow of data and the communication paths between devices. The type of logical topology chosen for a network can influence the type of Media Access Control (MAC) used. MAC protocols determine how devices on a network gain access to the communication medium and avoid collisions. Different logical topologies may require different MAC protocols to ensure efficient and reliable communication. Therefore, the statement "Influences the type of MAC used in the network" is true about the logical topology of a network.
7.
Which of the following protocols are typically used in WANs? (CHOOSE TWO)
Correct Answer(s)
C. HDLC
D. PPP
Explanation
HDLC (High-Level Data Link Control) and PPP (Point-to-Point Protocol) are typically used in WANs. HDLC is a synchronous data link layer protocol that provides error detection and flow control. It is commonly used in leased line connections. PPP is a data link layer protocol that provides a secure and reliable connection between two nodes. It is commonly used in dial-up connections and is also widely used in WAN connections. Ethernet and 802.11 are LAN protocols and are not typically used in WANs.
8.
Which of the following protocols are typically used in LANs? (CHOOSE TWO)
Correct Answer(s)
A. 802.11
B. Ethernet
Explanation
802.11 and Ethernet are typically used in LANs. 802.11 is a wireless protocol commonly known as Wi-Fi, which allows devices to connect to a network without the need for physical cables. Ethernet, on the other hand, is a wired protocol that uses cables to connect devices in a LAN. Both protocols are widely used in local area networks to enable communication between devices within a limited geographic area.
9.
Which of the following are common data link sublayers used in LANs? (Choose two.)
Correct Answer(s)
A. Protocol data unit
B. Logic Link Control
C. Media Access Control
Explanation
The correct answer is Protocol data unit, Logic Link Control, and Media Access Control. These three options are common data link sublayers used in LANs. The Protocol Data Unit (PDU) is the information that is being transmitted between two devices in a network. Logic Link Control (LLC) is responsible for error control and flow control in the data link layer. Media Access Control (MAC) is responsible for controlling access to the network media and ensuring that data is transmitted correctly. Network interface card and Carrier Access MultiAccess are not data link sublayers but rather hardware components used in LANs.
10.
To ensure that the content of the received frame at the destination matches that of the frame that left the source node, a transmitting node creates a logical summary of the contents of the frame. This is known as the CRC value. CRC means ________
Correct Answer(s)
Cyclic Redundancy Check
Explanation
The transmitting node creates a CRC value, which is a logical summary of the contents of the frame. This value is used to ensure that the content of the received frame at the destination matches that of the frame that left the source node. Therefore, the correct answer is "Cyclic Redundancy Check (CRC)".