CompTIA Network+ (N10-008) - Core Networking, OSI Layers & Protocols

List the 7 layers of the OSI model in order from top to bottom:
1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data Link
7. Physical

The Physical Layer is responsible for the physical transmission of raw bit streams over a physical medium. It defines hardware specifications like cables, connectors, and voltage levels (e.g., Ethernet cables, fiber optics).

The Data Link Layer provides node-to-node data transfer and handles error correction from the physical layer. It uses MAC addresses for addressing and organizes bits into frames. Examples include Ethernet and Wi-Fi.

The Network Layer is responsible for logical addressing (IP addresses) and routing data packets across different networks. It determines the best path for data delivery. The PDU is a packet.

The Transport Layer provides end-to-end communication services, including connection-oriented (TCP) and connectionless (UDP) data transfer. It segments data from the session layer and reassembles it. The PDU is a segment (TCP) or datagram (UDP).

List the 4 layers of the TCP/IP model and map them to the OSI model layers:
1. Application (OSI: Application, Presentation, Session)
2. Transport (OSI: Transport)
3. Internet (OSI: Network)
4. Network Access (OSI: Data Link, Physical)

DNS (Domain Name System) primarily uses UDP port 53 for name resolution queries. TCP port 53 is used for zone transfers between DNS servers.

HTTP (Hypertext Transfer Protocol) uses TCP port 80.
HTTPS (Hypertext Transfer Protocol Secure) uses TCP port 443.