Assessment 1.2 PDF

1.2.9 Lesson Review Candidate: Tai Chun Sam (sam33) Date: 12/26/2024, 9:22:34 AM Time Spent: 32:38 Score: 80% Passing Score: 80% Question 1. Correct...

1.2.9 Lesson Review Candidate: Tai Chun Sam (sam33) Date: 12/26/2024, 9:22:34 AM Time Spent: 32:38 Score: 80% Passing Score: 80% Question 1. Correct Which of the following are layers of the OSI reference model? (Select three.) Transmission Layer Application Layer Presentation Layer Session Layer Encryption Layer Connection Layer WAN Layer Explanation The following are layers of the OSI reference model: The Application Layer is the seventh layer of the OSI model and provides network services directly to the user's applications, such as email, file transfer, and other network software services. The Presentation Layer is the sixth layer of the OSI model and is responsible for the translation, encryption, and compression of data. It ensures that data is in a readable format for the Application Layer. The Session Layer is the fifth layer of the OSI model and establishes, manages, and terminates connections between applications. It is responsible for setting up, coordinating, and terminating conversations, exchanges, and dialogues between the applications at each end. Transmission Layer is not a layer of the OSI model. This might be confused with the Transport Layer, which is the fourth layer of the OSI model and is responsible for providing transparent transfer of data between end systems. Encryption Layer is not a layer of the OSI model. Encryption can occur at several layers, including the Presentation Layer and the Application Layer, but it is not a separate layer. WAN is a Wide Area Network and describes a network topology and not a layer in the OSI model. Connection Layer is not a layer of the OSI model. This might be confused with the Data Link Layer, which is the second layer of the OSI model and provides node-to-node data transfers between two directly connected nodes. References 1.2.1 Open Systems Interconnection Model 1.2.3 Layer 1 - Physical 1.2.8 OSI Model Summary 1.3.2 Physical Layer Functions 13.1.1 Wide Area Networks and the OSI Model resources\text\t_osi_n09\q_osi_layers_n09.question.xml Question 2. Correct What is a Protocol Data Unit (PDU)? A type of encryption used in data transmission A device that manages data transmission rates A measure of data transmission speed A chunk of data with protocol-specific headers added at each OSI layer Explanation A Protocol Data Unit (PDU) is the term used to describe the form that data takes at each layer of the OSI model. As data traverses down the layers on the sending node, each layer encapsulates the data by adding its specific headers (and sometimes footers), creating a PDU appropriate for that layer. This process ensures that data can be correctly processed, transmitted, and understood at each stage of its journey. A PDU is not a device but a structured form of data as it is handled by network protocols. A PDU refers to the format of data within network protocols, not a measure of speed. A PDU pertains to the structure of data for protocol processing, not a method of encryption. References 1.2.2 Data Encapsulation and Decapsulation 14.4.6 Overlay Networks resources\text\t_data_encapsulation_n09\q_data_encapsulation_pdu_role_n09.que Question 3. Correct What is the primary purpose of data encapsulation in network protocols? To encrypt data for secure transmission To convert data into an analog signal for transmission To compress data for faster transmission To add additional data headers for routing and delivery Explanation Data encapsulation is a fundamental process in network communication, where data at each layer of the OSI model is wrapped with protocol-specific headers (and sometimes footers). These headers provide essential information such as source and destination addresses, error checking, and more, which are necessary for the correct routing and delivery of data across a network. This process ensures that data packets are handled appropriately at each hop along their path to the destination. Encapsulation is not about compressing data but organizing it for transmission. Compression is a separate process that might be applied to data before encapsulation. Encapsulation itself does not involve encryption. Encryption may be applied to data as part of the security protocols at various layers but is distinct from the encapsulation process. Encapsulation deals with the digital organization of data for transmission, not the conversion of digital signals to analog. The conversion to analog signals, if necessary, is handled at the Physical layer, separate from the encapsulation process. References 1.2.2 Data Encapsulation and Decapsulation 14.4.6 Overlay Networks resources\text\t_data_encapsulation_n09\q_data_encapsulation_primary_purpose_ Question 4. Correct An engineer uses a type of network adapter to connect a fiber link to a router. The transceiver fits into an optical interface on a layer 3 Ethernet router. Of the choices, which layer 1 implementation does the engineer utilize? Media converter Switch Bridge VoIP endpoint Explanation Media converters are layer 1 devices and are used to convert one cable type to another. These components alter the characteristics of one type of cable to match those of another. A switch is a layer 2 device. Switches can handle traffic based on a node's physical address which is also known as a Media Access Control (MAC) address. A bridge is a layer 2 appliance or application that connects different networks as if they were one network. A VoIP (Voice over Internet Protocol) endpoint is a phone system component that can be implemented as software running on a computer or smartphone, or as a dedicated traditional handset. References 1.2.1 Open Systems Interconnection Model 1.2.3 Layer 1 - Physical 1.2.8 OSI Model Summary 1.3.2 Physical Layer Functions 13.1.1 Wide Area Networks and the OSI Model resources\text\t_layer1_n09\q_layer1_media_converter_n09.question.xml Question 5. Correct A communications engineer notices that every time it rains the signal becomes very degraded. Which layer of the OSI model is the engineer most likely troubleshooting? Data Link Transport Application Physical Explanation The physical layer (PHY) of the OSI model (layer 1) is responsible for the transmission and receipt of the signals that represent bits of data from one node to another node. Wireless is one medium. The data link layer (layer 2) is responsible for transferring data between nodes on the same logical segment. At the transport layer on the sending host, the system packages data from the upper layers as a series of layer 4 protocol data units (PDUs), referred to as segments. The application layer (layer 7) is at the top of the OSI stack. An application-layer protocol does not encapsulate any other protocols or provide services to any protocol. References 1.2.1 Open Systems Interconnection Model 1.2.3 Layer 1 - Physical 1.2.8 OSI Model Summary 1.3.2 Physical Layer Functions 13.1.1 Wide Area Networks and the OSI Model resources\text\t_layer1_n09\q_layer1_physical_02_n09.question.xml Question 6. Correct Which of the following devices operate at the Data Link layer of the OSI model? (Select three.) Routers Gateways Repeaters Hubs Network interface cards (NICs) Bridges Switches Explanation Network interface cards (NICs), bridges, and switches all operate at the OSI Data Link layer. They use the physical device address (MAC address) to identify packets. Hubs and repeaters operate at the Physical layer. They simply repeat packets without regard to addresses. Routers and gateways function at the Network layer. They examine the logical device and network address to perform routing tasks. References 1.2.1 Open Systems Interconnection Model 1.2.4 Layer 2 - Data Link 1.2.8 OSI Model Summary 1.3.3 Data Link Layer Functions 4.1.2 Layer 2 vs Layer 3 Addressing and Forwarding 13.1.1 Wide Area Networks and the OSI Model resources\text\t_layer2_n09\q_layer2_data_link_03_n09.question.xml Question 7. Incorrect When the Data Link layer performs encapsulation, it adds control information to the payload in the form of header fields. Which of the following are header fields added by the Data Link layer during encapsulation? (Select three.) TTL (Time to Live) Destination hardware address Sequence number Source hardware address Encryption type Checksum for basic error checking Window size Explanation The following are header fields added by the Data Link layer: Source hardware address: The source hardware address, also known as the source MAC address, is added to the frame by the Data Link layer to indicate the origin of the frame on the network. Destination hardware address: The destination hardware address, or destination MAC address, is included in the frame by the Data Link layer to ensure the frame reaches the correct device on the local network segment. Checksum for basic error checking: A checksum is a form of basic error checking added to the frame by the Data Link layer. It helps to verify that the frame has been received intact and without corruption during transmission. TTL is a field used at the Network layer within IP packets. It is used to limit the lifespan of a packet to prevent it from circulating indefinitely on the network. It is not added by the Data Link layer during encapsulation. Sequence numbers are used at the Transport layer to keep track of the order of a series of packets or segments. They are not part of the Data Link layer encapsulation process. Encryption types are related to the security protocols used to protect data during transmission, which are typically implemented at higher layers of the OSI model, such as the Presentation or Application layers, not at the Data Link layer. Window size is a concept used in flow control at the Transport layer to manage the amount of data that can be sent without receiving an acknowledgment. It is not a header field added by the Data Link layer during encapsulation. References 1.2.1 Open Systems Interconnection Model 1.2.4 Layer 2 - Data Link 1.2.8 OSI Model Summary 1.3.3 Data Link Layer Functions 4.1.2 Layer 2 vs Layer 3 Addressing and Forwarding 13.1.1 Wide Area Networks and the OSI Model resources\text\t_layer2_n09\q_layer2_header_fields_n09.question.xml Question 8. Correct What is the role of an Access Control List (ACL) at Layer 3 (Network layer) of the OSI model? To serve as a list of permissions for file access on the network To filter network traffic by permitting or blocking packets based on IP addresses and other criteria To act as a routing protocol for determining the best path for data packets To define the maximum size for packets transmitted across the network Explanation At Layer 3, ACLs are used to enforce security policies by filtering traffic. They determine which packets are allowed to pass through a network device, such as a router, based on rules that include IP addresses, protocol types, ports, and other criteria. ACLs do not define packet sizes; this is typically managed by the network protocols in use, such as TCP/IP. ACLs are not routing protocols. Routing protocols like OSPF or BGP are used to determine the best path for data packets. ACLs at Layer 3 do not manage file access permissions; they control network traffic. File access permissions are typically managed by the operating system or file system. References 1.2.1 Open Systems Interconnection Model 1.2.5 Layer 3 - Network 1.2.8 OSI Model Summary 1.3.4 Network Layer Functions  1.3.6 The Internet 1.3.7 Binary and Hexadecimal 4.1.2 Layer 2 vs Layer 3 Addressing and Forwarding 13.1.1 Wide Area Networks and the OSI Model 14.3.5 Cloud Firewall Security resources\text\t_layer3_n09\q_layer3_acls_n09.question.xml Question 9. Correct In the OSI model, what is the primary function of the Network layer? The primary function of the Network layer is to move data around an internetwork using logical network and host IDs. The primary function of the Network layer is to encode and convert data into signals suitable for transmission over the physical medium. The primary function of the Network layer is to ensure reliable transmission of data across a physical link. The primary function of the Network layer is to establish, manage, and terminate connections between applications on different hosts. Explanation The primary function of the Network layer is to move data around an internetwork using logical network and host IDs. The Network layer, or Layer 3 of the OSI model, is responsible for the logical addressing of data and its delivery across different networks, or an internetwork. It uses logical addresses, such as IP addresses, to ensure data packets are routed to the correct destination network and ultimately to the correct host within that network. Routers, which operate at this layer, use the information contained in the packet's network layer header to make forwarding decisions, guiding the packet through the internetwork hop by hop until it reaches its destination. Encoding and converting data into signals suitable for transmission over the physical medium is the primary function of the Physical layer, or Layer 1 of the OSI model. Layer 1 is responsible for the transmission and reception of raw bit streams over a physical medium. It deals with the electrical, mechanical, procedural, and functional aspects of the physical connection between devices. Establishing, managing, and terminating connections between applications on different hosts is the primary function of the Session layer, or Layer 5 of the OSI model. The Session layer is responsible for setting up, managing, and then tearing down sessions between presentation layer entities on different hosts. It provides mechanisms for controlling the dialogue between the two hosts, including synchronization and checkpointing. Ensuring reliable transmission of data across a physical link is the primary function of the Transport layer, or Layer 4 of the OSI model. The Transport layer is responsible for providing reliable data transfer services to the upper layers. This includes the segmentation of data, acknowledgment of receipt, error correction through retransmission, and flow control. References 1.2.1 Open Systems Interconnection Model 1.2.5 Layer 3 - Network 1.2.8 OSI Model Summary 1.3.4 Network Layer Functions 1.3.6 The Internet 1.3.7 Binary and Hexadecimal 4.1.2 Layer 2 vs Layer 3 Addressing and Forwarding 13.1.1 Wide Area Networks and the OSI Model 14.3.5 Cloud Firewall Security resources\text\t_layer3_n09\q_layer3_description_n09.question.xml Question 10. Correct Which of the following functions are performed by the OSI Transport layer? (Select three.) Packet formatting for delivery through a medium Data segmentation and reassembly Media access control, logical topology, and device identification Consistent data formatting between dissimilar systems Path identification and selection End-to-end flow control Reliable message delivery Explanation The Transport layer is responsible for breaking upper-layer data into segments and allowing reliable communication through end-to-end flow control, error detection, and error correction. Message transmission through a medium is performed at the Physical layer. Media access, logical topology, and device identification occur at the Data Link layer. Path identification and selection is a function of the Network layer. Data formatting is performed at the Presentation layer. References 1.2.1 Open Systems Interconnection Model 1.2.6 Layer 4 - Transport 1.2.8 OSI Model Summary 1.3.5 Transport and Application Layer and Security Functions 1.3.7 Binary and Hexadecimal  14.3.5 Cloud Firewall Security resources\text\t_layer4_n09\q_layer4_functions_n09.question.xml Question 11. Incorrect A security engineer configures software-based port security on a hardware firewall. Which OSI model layer identifies the application ports to configure? Layer 3 Layer 1 Layer 4 Layer 2 Explanation The transport layer (layer 4) manages end-to-end communications. At layer 4, a port number identifies each application, such as 80 for hypertext transfer protocol (HTTP) web traffic. Layer 1 (the physical layer) uses physical ports and cabling to connect and create a local area network. Ethernet switching by using hardware-based media access control (MAC) addresses and wireless to wired bridging make use of physical layer adapters at layer 2. At layer 3, the network layer, the routing part of the router (such as a SOHO router), makes forwarding decisions between the local private network and the public Internet. References 1.2.1 Open Systems Interconnection Model 1.2.6 Layer 4 - Transport 1.2.8 OSI Model Summary 1.3.5 Transport and Application Layer and Security Functions 1.3.7 Binary and Hexadecimal 14.3.5 Cloud Firewall Security resources\text\t_layer4_n09\q_layer4_ports_n09.question.xml Question 12. Correct What role does the Presentation layer (layer 6) of the OSI model play in terms of data compression and encryption? The Presentation layer handles the routing of data between different networks and supports encryption protocols like IPsec. The Presentation layer supports data compression and encryption to prepare data for network transmission. The Presentation layer is primarily responsible for the physical encryption of data using hardware-based methods. The Presentation layer is involved in the logical organization of data into frames for transmission. Explanation The Presentation layer transforms data to ensure that it is in the correct format for the application or network. This includes data compression to reduce the size of the data for transmission and encryption to secure the data during transfer. The Presentation layer deals with data transformation and representation, not physical encryption methods, which are typically implemented at lower layers or by specific security hardware. The logical organization of data into frames is a function of the Data Link layer (layer 2) of the OSI model. Routing is a function of the Network layer (layer 3), and while the Presentation layer can be involved in encryption, IPsec is a protocol that operates at the Network layer, not the Presentation layer. References 1.2.1 Open Systems Interconnection Model 1.2.7 Upper Layers 1.2.8 OSI Model Summary resources\text\t_layer5_n09\q_layer5_presentation_02_n09.question.xml Question 13. Correct Which of the following statements accurately describes the function of the Session layer (layer 5) in the OSI model? The Session layer is used for character set conversion, such as between ASCII and Unicode. The Session layer administers the process of establishing, managing, and terminating a dialog between client and server. The Session layer provides the physical transmission of data over network media. The Session layer is responsible for routing packets across different networks. Explanation The correct answer is that the Session layer administers the process of establishing, managing, and terminating a dialog between client and server. The Session layer is crucial for controlling the dialog between two computers or network devices. It establishes, manages, and terminates connections, ensuring that data is properly synchronized and organized during communication sessions. The Session layer is responsible for routing packets across different networks is incorrect because routing is a function of the Network layer (layer 3) of the OSI model, not the Session layer. The Session layer provides the physical transmission of data over network media is incorrect because the physical transmission of data is the responsibility of the Physical layer (layer 1) of the OSI model. The Session layer is used for character set conversion, such as between ASCII and Unicode is incorrect because character set conversion is a function of the Presentation layer (layer 6), which is responsible for data representation and encoding, not the Session layer. References  1.2.1 Open Systems Interconnection Model 1.2.7 Upper Layers 1.2.8 OSI Model Summary resources\text\t_layer5_n09\q_layer5_session_n09.question.xml Question 14. Correct Match each networking function or device on the left with its associated OSI model layer on the right. Application layer HTTP Presentation layer Translates data Session layer Session ID number Transport layer Port number Network layer Router Data Link layer Switch Explanation The following describes how devices function at different layers of the OSI model: HTTP functions at the Application layer. Encapsulation happens at the Presentation layer. Session IDs are assigned at the Session layer. Port numbers are assigned at the Transport layer. Routers function at the Network layer. Switches function at the Data Link layer. References 1.2.1 Open Systems Interconnection Model 1.2.3 Layer 1 - Physical 1.2.8 OSI Model Summary 1.3.2 Physical Layer Functions 13.1.1 Wide Area Networks and the OSI Model resources\text\t_osi_layers_n09\q_osi_layers_describe_n09.question.xml Question 15. Incorrect A network engineer is designing a network in various offices to create multiple broadcast domains. Each has its own Virtual Local Area Network (VLAN). When configuring these multiple broadcast domains on the switch, the switch will be operating at what layer of the OSI model? Layer 4 (Transport Layer) Layer 7 (Application Layer) Layer 2 (Data Link Layer) Layer 1 (Physical Layer) Explanation Layer 2 (Datalink Layer) is the correct answer. VLANs (Virtual Local Area Networks) are a Layer 2 technology. When configuring VLANs on a switch, the network engineer is working at the Data Link Layer. This layer is responsible for segmenting the network into multiple broadcast domains using VLAN IDs. Devices like switches and bridges operate at this layer to manage MAC addresses and frames, which are essential for VLAN functionality. The Physical Layer is responsible for the physical connection between devices, including cables, transceivers, and media converters. It deals with the transmission and reception of raw bit streams over a physical medium. Configuring VLANs, which involves creating multiple broadcast domains, is not a function of the Physical Layer. The Transport Layer is responsible for end-to-end communication and error recovery. It deals with the segmentation and reassembly of data, as well as flow control and error correction. Configuring VLANs, which involves creating multiple broadcast domains, is not a function of the Transport Layer. The Application Layer is the topmost layer of the OSI model and is responsible for providing network services directly to end-users and applications. It deals with protocols like HTTP, FTP, and SMTP. Configuring VLANs, which involves creating multiple broadcast domains, is not a function of the Application Layer.  References 1.2.1 Open Systems Interconnection Model 1.2.5 Layer 3 - Network 1.2.8 OSI Model Summary 1.3.4 Network Layer Functions 1.3.6 The Internet 1.3.7 Binary and Hexadecimal 4.1.2 Layer 2 vs Layer 3 Addressing and Forwarding 13.1.1 Wide Area Networks and the OSI Model 14.3.5 Cloud Firewall Security resources\text\t_osi_layers_n09\q_osi_layers_network_n09.question.xml Copyright © The Computing Technology Industry Association, Inc. All rights reserved.