Module 1 Review Exam PDF

The **Data Link Layer** provides node-to-node data transfer and is responsible for error detection and correction from the Physical Layer. It ensures that data frames are properly formatted for transmission and reception between devices on the same network. This layer is divided into two sublayers:...

The **Data Link Layer** provides node-to-node data transfer and is responsible for error detection and correction from the Physical Layer. It ensures that data frames are properly formatted for transmission and reception between devices on the same network. This layer is divided into two sublayers: the Media Access Control (MAC) layer, which controls how devices on the network gain access to the data and permission to transmit it, and the Logical Link Control (LLC) layer, which controls frame synchronization, flow control, and error checking. This layer uses unique MAC addresses for each node on the same network and includes network interface cards (NICs), layer 2 switches, and bridges. The **Presentation Layer** translates data between the application layer and the network format. It handles data encryption, compression, and translation, ensuring that data is readable by the receiving system. This layer acts as a translator for the network, converting data into a format that the application layer can understand. Gateway devices operate at layer 6. The **Network Layer** is responsible for the logical addressing and routing of data packets between devices across different networks. It determines the best path for data transmission and manages the delivery of packets from the source to the destination. This layer uses IP addresses for routing and includes routers and layer 3 switches. The **Physical Layer** is the lowest layer of the OSI model and is concerned with the transmission and reception of raw data bits over a physical medium. It defines the hardware elements involved, such as cables, hubs, repeaters, and network interface cards (NICs). This layer handles the electrical, mechanical, and procedural aspects of network communication The **Transport Layer** ensures reliable data transfer between end systems and provides error recovery and flow control. It segments and reassembles data for communications between end devices and ensures complete data transfer. Common protocols operating at this layer include the Transmission Control Protocol (TCP), which ensures reliable, ordered delivery, and the User Datagram Protocol (UDP), which provides faster, but less reliable, data transmission. Load balancers, gateways, and layer 4 switches operate at this layer. The **Session Layer** establishes, manages, and terminates sessions between applications. It controls the dialog between systems, including session establishment, maintenance, and termination. This layer ensures that data streams are properly synchronized and maintained throughout the session. Gateway devices operate at layer 5. The **Application Layer** is the topmost layer and interacts directly with end-user applications. It provides network services to applications such as web browsers, email clients, and file transfer programs. This layer facilitates communication between software applications and the network, using protocols like HTTP, FTP, SMTP, and DNS. Devices that operate at layer 7 of the OSI model include firewalls, proxy servers, application load balancers, and multilayer switches.