OSI Model

A collection of vocabulary flashcards covering network protocols, the seven layers of the OSI model, port numbers, and the encapsulation process based on the CompTIA Network+ N10-009 course notes.

Protocol

A set of rules for formatting and processing data that enables computers to communicate regardless of software and hardware differences.

Open System Interconnection (OSI) Model

A model made up of seven layers used to organize and describe network functions to achieve interoperability of diverse vendor devices.

Layer 7 - Application

The entry door to network services that interfaces user applications, network management services, and remote access.

Simple Mail Transfer Protocol (SMTP)

An Application Layer protocol used for email transmission, associated with port $25$.

Simple Network Management Protocol (SNMP)

An Application Layer protocol used for network management, associated with port $161$.

Hypertext Transfer Protocol (HTTP)

An Application Layer protocol used for the World Wide Web, associated with port $80$.

File Transfer Protocol (FTP)

An Application Layer protocol used for file transfers, associated with port $21$.

Telnet

An Application Layer protocol used for remote access, associated with port $23$.

Trivial File Transfer Protocol (TFTP)

An Application Layer protocol used for simple file transfers, associated with port $69$.

Post Office Protocol version 3 (POP3)

An Application Layer protocol used for receiving email, associated with port $110$.

Internet Message Access Protocol (IMAP)

An Application Layer protocol used for accessing email on a server, associated with port $143$.

Layer 6 - Presentation

The layer concerned with data representation, conversion, character code translation, compression, and encryption/decryption.

ASCII

American Standard Code For Information Interchange; a character encoding standard at the Presentation Layer.

JPEG

Joint Photographic Experts Group; a standard for photographic data representation at the Presentation Layer.

Layer 5 - Session

The layer that provides logical persistent connections between peer hosts and manages the creation, monitoring, and tearing down of sessions.

Network File System (NFS)

A Session Layer protocol that allows a user on a client computer to access files over a network.

Structured Query Language (SQL)

A Session Layer language used for managing data held in a relational database management system.

Layer 4 - Transport

The layer responsible for end-to-end communication, reliability, and transport between peer hosts using TCP or UDP.

Transmission Control Protocol (TCP)

A full-duplex, connection-oriented and reliable protocol at the Transport Layer.

User Datagram Protocol (UDP)

A simplex, connectionless, 'best effort' protocol at the Transport Layer.

Well-Known Ports

The range of ports spanning from $0$ to $1023$.

Registered Ports

The range of ports spanning from $1024$ to $49151$.

Dynamic or Private Ports

The range of ports spanning from $49152$ to $65535$.

Layer 3 - Network

The layer responsible for path determination and logical addressing, primarily using the Internet Protocol (IP).

Internet Control Message Protocol (ICMP)

A Network Layer protocol used by network devices to send error messages and operational information.

Internet Group Management Protocol (IGMP)

A Network Layer protocol used by hosts and adjacent routers on IPv4 networks to establish multicast group memberships.

Layer 2 - Data Link

The layer that transmits frames, detects errors, and uses MAC/Hardware addresses to communicate within the same network.

Media Access Control (MAC) layer

A sublayer of the Data Link Layer that manages protocol access to the physical network medium and handles physical addressing.

Logical Link Control (LLC) layer

The upper sublayer of the Data Link Layer that provides flow control and error control.

Address Resolution Protocol (ARP)

A Data Link Layer protocol used to resolve IP addresses into MAC addresses.

Reverse Address Resolution Protocol (RARP)

A Data Link Layer protocol used to resolve MAC addresses into IP addresses.

Layer 1 - Physical

The layer responsible for converting bits into electrical, light, or radio signals and handling physical topologies and media.

Encapsulation

The process of wrapping data in specific protocols as it moves down the OSI model (Data -> Segment -> Packet -> Frame -> Bits).

De-encapsulation

The process of unwrapping data protocol headers as it moves up the OSI model from bits to the application layer.

Segment / Datagram

The Protocol Data Unit (PDU) at the Transport Layer (Layer 4).

Packet

The Protocol Data Unit (PDU) at the Network Layer (Layer 3).

Frame

The Protocol Data Unit (PDU) at the Data Link Layer (Layer 2).

Bits

The Protocol Data Unit (PDU) at the Physical Layer (Layer 1).