Computer Networking Glossary — Key Terms and Definitions

ACK (Acknowledgment): A signal sent by a receiver to confirm that a packet of data has been successfully received.

Bandwidth: The maximum rate of data transfer across a network path, measured in bits per second (bps).

Broadcast: A data packet sent to all devices on a network segment. Limited by broadcast domain.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection): A protocol used in Ethernet networks to manage data transmission and handle collisions.

DNS (Domain Name System): A hierarchical system translating human-readable domain names (e.g., example.com) into IP addresses.

Encapsulation: The process of adding headers and trailers to data as it moves down the protocol stack.

Ethernet: A family of wired computer networking technologies commonly used in local area networks (LANs).

Gateway: A network node that serves as an access point to another network, often performing protocol conversion.

Hexadecimal: A base-16 number system used to represent binary data concisely. Common in MAC and IP addresses.

Hop: The passage of a data packet from one network segment to the next, typically through a router.

Internet: A global system of interconnected computer networks using the TCP/IP protocol suite.

Intranet: A private network accessible only to authorized personnel within an organization.

Latency: The time delay for data to travel from source to destination. Measured in milliseconds (ms).

MAC Address (Media Access Control): A unique identifier assigned to a network interface controller. 48-bit address, e.g., 00:1A:2B:3C:4D:5E.

NIC (Network Interface Card): A hardware component connecting a computer to a computer network.

Node: A connection point in a network that can receive, create, store, or send data.

Packet: A unit of data formatted for transmission across a network. Contains header (addressing) and payload (data).

Payload: The actual data carried by a packet, excluding headers and metadata.

Protocol: A set of rules governing communication between devices on a network.

Router: A networking device that forwards data packets between networks. Operates at Layer 3 of the OSI model.

Switch: A networking device that connects devices within a LAN, forwarding data based on MAC addresses. Layer 2.

Topology: The arrangement of elements in a network. Types: bus, star, ring, mesh, hybrid.

Unicast: A one-to-one communication between a single sender and a single receiver.

ARP (Address Resolution Protocol): Maps IP addresses to MAC addresses within a local network.

DHCP (Dynamic Host Configuration Protocol): Automatically assigns IP addresses and network configuration to devices.

DNS (Domain Name System): Resolves domain names to IP addresses. Uses port 53 (UDP/TCP).

HTTP (HyperText Transfer Protocol): Application-layer protocol for transmitting web pages. Uses port 80.

HTTPS (HTTP Secure): HTTP with TLS/SSL encryption. Uses port 443. Secure web communication.

ICMP (Internet Control Message Protocol): Used for diagnostic and error-reporting purposes. Used by ping.

IGMP (Internet Group Management Protocol): Manages multicast group memberships for IP multicast.

IP (Internet Protocol): Responsible for addressing and routing packets. Versions: IPv4, IPv6.

IPv4: 32-bit address space providing approximately 4.3 billion unique addresses. Dotted decimal: 192.168.1.1.

IPv6: 128-bit address space providing approximately 3.4 × 10³⁸ unique addresses. Written in hexadecimal.

NAT (Network Address Translation): Translates private IP addresses to public IP addresses for internet access.

OSPF (Open Shortest Path First): A link-state routing protocol used within autonomous systems.

POP3 (Post Office Protocol version 3): An email protocol for retrieving messages from a mail server. Downloads emails.

SMTP (Simple Mail Transfer Protocol): An email protocol for sending messages between servers. Uses port 25/587.

SNMP (Simple Network Management Protocol): For managing and monitoring network devices. Uses ports 161/162.

SSH (Secure Shell): A cryptographic network protocol for secure remote access. Uses port 22.

TCP (Transmission Control Protocol): A reliable, connection-oriented protocol ensuring ordered delivery of data.

Telnet: A protocol for remote command-line access. Unencrypted; replaced by SSH for security.

TLS/SSL (Transport Layer Security/Secure Sockets Layer): Cryptographic protocols providing secure communication over a network.

UDP (User Datagram Protocol): A connectionless protocol sending data without establishing a connection. Faster but unreliable.

Application Layer (Layer 7): The layer closest to the end user, providing network services to applications. Examples: HTTP, FTP, SMTP.

Data Link Layer (Layer 2): Provides node-to-node data transfer between directly connected nodes. Handles MAC addresses and error detection.

Network Layer (Layer 3): Handles routing and forwarding of data packets between different networks. Handles IP addressing.

Physical Layer (Layer 1: The lowest layer, dealing with the physical transmission of raw bits over a communication channel.

Presentation Layer (Layer 6): Translates, encrypts, and compresses data between the application and network formats.

Session Layer (Layer 5): Manages sessions (connections) between applications. Establishes, maintains, and terminates connections.

Transport Layer (Layer 4): Provides end-to-end communication services. Handles segmentation, flow control, and error recovery. TCP, UDP.

Access Point: A networking device that allows wireless devices to connect to a wired network.

Bridge: A device that connects two or more network segments at the data link layer, filtering traffic.

Cable: Physical medium for transmitting data. Types: twisted pair, coaxial, fiber optic.

Coaxial Cable: A cable with a central conductor surrounded by insulation and a metallic shield. Used in cable TV and internet.

Fiber Optic Cable: A cable using glass or plastic fibers to transmit data as light pulses. High bandwidth, low interference.

Hub: A basic networking device that broadcasts data to all connected devices. Largely replaced by switches.

Load Balancer: A device distributing network traffic across multiple servers to optimize performance.

Modem (Modulator-Demodulator): Converts digital signals to analog and vice versa for transmission over telephone or cable lines.

Patch Panel: A panel of ports used to manage and organize network cable connections.

Repeater: A device that regenerates and amplifies signals to extend network reach.

Server: A computer that provides services to other computers (clients) on the network.

Twisted Pair Cable: A cable with pairs of insulated copper wires twisted together. Categories: Cat5, Cat6, Cat7.

VPN (Virtual Private Network): Creates a secure, encrypted connection over a public network. Provides privacy and remote access.

Wireless Router: A networking device that combines a router, switch, and wireless access point.

Authentication: The process of verifying the identity of a user, device, or system.

Authorization: Determining what an authenticated user is allowed to do or access.

Brute Force Attack: An attack trying all possible combinations of passwords or keys until the correct one is found.

Certificate Authority (CA): A trusted entity that issues digital certificates for TLS/SSL encryption.

Cryptography: The practice of securing communication through encryption and decryption of data.

DDoS (Distributed Denial of Service): An attack where multiple compromised systems flood a target with traffic.

Dictionary Attack: An attack using a pre-listed list of common passwords to gain unauthorized access.

Digital Certificate: An electronic document proving the ownership of a public key. Used in TLS/SSL.

Encryption: The process of converting data into a coded format to prevent unauthorized access.

Firewall: A network security system monitoring and controlling incoming and outgoing traffic based on rules.

IDS/IPS (Intrusion Detection/Prevention System): Monitors network traffic for suspicious activity and blocks potential threats.

Keylogger: Software that records keystrokes to capture sensitive information like passwords.

Man-in-the-Middle Attack: An attack where an attacker intercepts communication between two parties.

Phishing: A social engineering attack using fraudulent emails or websites to steal sensitive information.

Ransomware: Malware that encrypts a victim’s data and demands payment for decryption.

Social Engineering: Manipulating people into divulging confidential information or performing actions.

Spyware: Software that secretly monitors and collects information about a user.

Virus: A malicious program that replicates itself and spreads to other computers.

Worm: A standalone malicious program that self-replicates and spreads across networks.

Zero-Day Exploit: An attack exploiting a previously unknown vulnerability before a patch is available.

ARP Table: A table mapping IP addresses to MAC addresses, maintained by the ARP protocol.

Bandwidth Test: A measurement of the maximum data transfer rate of a network connection.

DNS Lookup: The process of resolving a domain name to an IP address using DNS servers.

IP Configuration: The settings determining how a device connects to a network (IP address, subnet mask, gateway).

Packet Loss: The failure of data packets to reach their destination, causing retransmissions and delays.

Ping: A utility using ICMP to test connectivity and measure round-trip time to a network host.

Route Tracing: The process of tracking the path packets take through a network. Tool: traceroute/tracert.

Throughput: The actual rate of successful data transfer across a network, measured in bps.

Traceroute: A diagnostic tool showing the path and latency of packets across an IP network.

Wireshark: A network protocol analyzer for capturing and inspecting network traffic in real-time.

• Networking Fundamentals Guide
• TCP/IP Deep Dive
• Network Security Overview
• Troubleshooting Guide