The OSI model Flashcards
What is the Application Layer (Layer 7), and what is its primary function?
The Application Layer enables user interaction with the internet through software applications. It includes protocols like HTTP/HTTPS (for web browsing), SMTP (for email), and DNS (for translating domain names to IP addresses). This layer is where user requests and responses are initiated and processed.
How does the Application (Layer 7) facilitate web browsing?
When a user accesses a website, the browser uses HTTP or HTTPS to send requests to the web server and receive responses. DNS is also used to translate domain names (e.g., www.example.com) into IP addresses to locate the server hosting the website.
What is the Presentation Layer (Layer 6), and what are its key responsibilities?
The Presentation Layer ensures data is in a format that applications on both sending and receiving systems can understand. It handles data translation, encryption (e.g., SSL for HTTPS), compression, and character encoding to ensure compatibility across systems.
Why is encryption important at the Presentation Layer (6)?
Encryption, such as SSL/TLS, secures data during transmission, protecting sensitive information (e.g., passwords, credit card details) from being intercepted or accessed by unauthorized parties.
What is the Session Layer (Layer 5), and what role does it play in network communication?
The Session Layer establishes, maintains, and terminates connections (sessions) between devices. It manages authentication, reconnection, and checkpoints during data transfer. If a session is interrupted, it ensures the transmission resumes from the last checkpoint.
How does the Session Layer handle (5) interruptions in data transfer?
It uses checkpoints to mark progress during data transfer. If a session is interrupted, the transfer resumes from the last checkpoint, ensuring no data is lost or duplicated.
What is the Transport Layer (Layer 4), and what are its main functions?
What is the Transport Layer (Layer 4), and what are its main functions?
What is the difference between TCP and UDP at the Transport Layer (4)?
TCP (Transmission Control Protocol): Establishes a connection, ensures reliable delivery, and retransmits lost data.
UDP (User Datagram Protocol): Connectionless, faster, but does not guarantee delivery or retransmit lost data. Used for real-time applications like video streaming.
What is the Network Layer (Layer 3), and what is its primary role?
The Network Layer is responsible for routing data packets between devices across different networks. It uses IP addresses to identify the source and destination, ensuring packets are delivered to the correct location. Routers operate at this layer.
How does the Network Layer (3) use IP addresses?
IP addresses are attached to data packets to identify the sender and receiver. Routers use these addresses to determine the best path for delivering packets between networks.
What is the Data Link Layer (Layer 2), and what does it do?
The Data Link Layer organizes data transmission within a single network. It handles framing (packaging data into frames), error detection, and MAC addressing. Switches and network interface cards (NICs) operate at this layer.
What are examples of protocols used at the Data Link Layer (2)?
Protocols like NCP (Network Control Protocol), HDLC (High-Level Data Link Control), and SDLC (Synchronous Data Link Control) are used to manage data transmission within a network.
What is the Physical Layer (Layer 1), and what is its function?
The Physical Layer deals with the physical transmission of data over hardware (e.g., cables, hubs, modems). It converts data into binary (0s and 1s) for transmission over wired or wireless media.
How does the Physical Layer(1) transmit data?
Data is converted into electrical, optical, or radio signals (binary 0s and 1s) and transmitted over physical media like Ethernet cables, fiber optics, or Wi-Fi. The receiving device then decodes the signals back into data.
