AP Cyber — Networking & Number Systems

Flashcards covering key vocabulary terms and definitions from AP Cyber lecture notes on Networking Theory, Topologies, Number Systems, Cabling, Addressing, IP Assignment, OSI Model, and TCP vs UDP.

Network

Two or more computers connected to share resources (files, applications, OS, printers, etc.).

LAN (Local Area Network)

A network designed for local sharing, typically inside an office, school, or building.

WAN (Wide Area Network)

A network that connects multiple LANs across large geographic areas.

Scalability

How easily a network can grow, for example, by adding new PCs.

Fault Tolerance/Redundancy

The ability of a network to survive if one cable or switch fails.

Latency

The time it takes a packet to reach its destination, often increased by congested links.

Point-to-Point Topology

A network topology connecting one device directly to another, e.g., computer to printer.

Bus Topology

A network topology where devices connect to one backbone cable; cheap, but backbone failure causes the whole network to go down.

Ring Topology

A network topology where devices form a closed loop, and data passes in one direction using 'token passing'; outdated for modern LANs.

Star Topology

A network topology where each device connects to a central hub/switch; common in homes, but central hub failure causes all devices to fail.

Hub-and-Spoke Topology

Similar to a star topology but used for WANs, with branch offices (spokes) connecting to a central office hub.

Mesh Topology

A network topology where devices connect to many others, offering very high reliability but being expensive; used in critical networks like military.

Hybrid Topology

A network topology that combines elements of different topologies, e.g., star-bus.

Spine-Leaf Topology

A data center network design where leaf switches connect servers, and spine switches interconnect leaves for redundancy.

Binary (Base 2)

A number system used by computers, based on two states (0 and 1) representing off and on transistors.

Decimal (Base 10)

The standard number system humans use, with digits 0-9.

Hexadecimal (Base 16)

A number system using digits 0-9 and letters A-F, often used as a shorthand for binary due to being easier for humans to read.

Octal (Base 8)

A number system using digits 0-7, often used by grouping binary bits into threes.

ASCII

A standard that converts characters into binary numbers.

RGB values

Binary values that represent colors, e.g., for digital images.

Bitmaps

Digital images where each pixel stores RGB values in binary format.

Twisted Pair Cable

Copper wires twisted together to reduce electromagnetic interference, commonly used for Ethernet.

Cat5e Cable

An Ethernet cable category capable of speeds up to 1 Gbps.

Cat6 Cable

An Ethernet cable category capable of speeds up to 10 Gbps.

Coaxial Cable

A cable with a copper core and shielding, used in older broadband internet connections.

Fiber Optic Cable

A cable that uses light pulses for data transmission, offering the fastest speeds, long-distance capabilities, and immunity to interference.

RJ-45

A standard connector used for Ethernet cables.

Crosstalk Interference

Electrical interference that occurs between adjacent wires, reduced by twisting wire pairs.

MAC Address (Physical Address)

A manufacturer-assigned, unique hardware address (e.g., 00-1A-92-7C-4E-01) used at the Data Link layer.

IP Address (Logical Address)

A numerical label assigned to each device connected to a computer network, used for identification and location (IPv4 is 32-bit, IPv6 is 128-bit).

Port Address

A number that identifies a specific application or service on a device, e.g., TCP port 80 for HTTP.

Application-specific Address

Addresses used at the application layer, such as URLs (www.example.com) or email addresses.

0.0.0.0 (IPv4)

A reserved IPv4 address indicating a host without an assigned IP address.

127.0.0.* (IPv4)

The loopback address range in IPv4, used for testing local network interfaces.

255.255.255.255 (IPv4)

The broadcast address in IPv4, sending data to all devices on the local network.

Private IP Block 192.168.x.x

A range of private IPv4 addresses reserved for use within local networks, not routable on the public internet.

Private IP Block 10.x.x.x

A range of private IPv4 addresses reserved for use within local networks, not routable on the public internet.

Private IP Block 172.16-31.x.x

A range of private IPv4 addresses reserved for use within local networks, not routable on the public internet.

Public IP Address

An IP address assigned by an ISP, visible and routable on the internet.

Private IP Address

An IP address used for internal networks, not routable directly on the internet.

Static IP Address

An IP address that is manually configured and does not change.

Dynamic IP Address

An IP address that is automatically assigned by a DHCP server and may change over time.

Gateway

The IP address of the router used to leave the local area network (LAN) and access other networks like the internet.

ARP (Address Resolution Protocol)

A protocol used to map an IP address to a MAC address on a local area network.

RARP (Reverse Address Resolution Protocol)

A protocol used to map a MAC address to an IP address.

DNS (Domain Name System)

A hierarchical distributed naming system that translates human-readable domain names (like www.example.com) into numerical IP addresses.

SSL/TLS (Secure Sockets Layer/Transport Layer Security)

Cryptographic protocols providing communication security over a computer network, commonly used for HTTPS encryption.

Unicast

A network communication type where data is sent from one device to one other device.

Multicast

A network communication type where data is sent from one device to multiple subscribed hosts.

Broadcast (Network Communication)

A network communication type (only in IPv4) where data is sent from one device to all other devices on the local network.

Anycast

An IPv6 network communication type where data is sent from one device to the topologically 'nearest' of several potential receivers.

DHCP (Dynamic Host Configuration Protocol)

A network management protocol used on IP networks for dynamically assigning IP addresses and other communication parameters to devices connected to the network.

DORA (DHCP Process)

Acronym for the four steps of the DHCP process: Discover, Offer, Request, Acknowledge.

APIPA (Automatic Private IP Addressing)

A feature that allows a device to self-assign an IP address in the 169.254.x.x range if no DHCP server is available, providing local LAN communication but no internet access.

DHCPv6

The version of DHCP used for assigning IP addresses and other network configuration parameters to devices on IPv6 networks.

SLAAC (Stateless Address Autoconfiguration)

An IPv6 feature allowing a host to automatically create its own IP address from a router's prefix and its own MAC address without a DHCP server.

Global Unicast (IPv6)

Publicly routable IPv6 addresses, analogous to public IPv4 addresses (e.g., 2001:…).

Link Local (IPv6)

IPv6 addresses (FE80:…) that only work within the local area network (LAN) and are not routable beyond it.

Loopback (IPv6)

The IPv6 loopback address, ::1, used for testing a device's own network capabilities.

OSI Model

A conceptual framework created in the 1980s to standardize how different network components communicate, organized into seven distinct layers.

Physical Layer (OSI)

Layer 1 of the OSI model, dealing with the physical transmission of raw bit streams over a medium (cables, fiber, wireless signals).

Data Link Layer (OSI)

Layer 2 of the OSI model, responsible for MAC addressing, error detection, and frame transmission between directly connected network nodes.

Network Layer (OSI)

Layer 3 of the OSI model, responsible for routing data packets between different networks using logical IP addressing.

Transport Layer (OSI)

Layer 4 of the OSI model, responsible for end-to-end communication, segmenting data, and ensuring reliable (TCP) or fast (UDP) delivery.

Session Layer (OSI)

Layer 5 of the OSI model, responsible for establishing, managing, and terminating communication sessions between applications.

Presentation Layer (OSI)

Layer 6 of the OSI model, responsible for data translation, encryption, and compression, ensuring data is in a format usable by the application layer (e.g., JPEG, MPEG).

Application Layer (OSI)

Layer 7 of the OSI model, which provides network services directly to end-user applications (e.g., web browsing, email, streaming).

Encapsulation (Networking)

The process where each layer of the OSI model adds its own header (PDU) to the data received from the layer above it, preparing it for transmission.

PDU (Protocol Data Unit)

The unit of data at any given layer of the OSI model (e.g., bits at Physical, frames at Data Link, packets at Network, segments at Transport).

TCP (Transmission Control Protocol)

A Transport Layer protocol that provides reliable, ordered, and error-checked delivery of data with a 3-way handshake; used for HTTP, FTP, Email.

3-way handshake (TCP)

The process TCP uses to establish a connection (SYN → SYN-ACK → ACK) before data transfer begins, ensuring reliability.

UDP (User Datagram Protocol)

A Transport Layer protocol that provides fast, connectionless, and unreliable data transmission without a handshake; used for online gaming, video streaming, VoIP.