Networking Fundamentals: Addressing, Physical Layer, Ethernet, and Wireless Networks

A comprehensive vocabulary review of core computer networking concepts covering IPv4 addressing and segmentation, 802.11 wireless fundamentals, Ethernet specifications and switching, physical layer media and cabling, and layered network communication models.

Dotted-Decimal Notation

A representation of a $32\text{-bit}$ IPv4 address partitioned into four $8\text{-bit}$ octets, with each octet converted to a decimal number ranging from $0$ to $255$ separated by periods.

Subnet Mask

A $32\text{-bit}$ sequence of continuous $1\text{s}$ followed by continuous $0\text{s}$ used by a host to distinguish the network portion from the host portion of an IPv4 address.

Prefix Length

A shorthand notation (such as $/24$) that specifies the number of consecutive binary $1\text{s}$ in a subnet mask.

Logical AND

A bitwise Boolean operation performed between an IPv4 address and its subnet mask yielding a $1$ only when both operand bits are $1$, used by network devices to compute the network address.

RFC 1918

The standard defining the private IPv4 address blocks reserved for internal networks: $10.0.0.0/8$, $172.16.0.0/12$, and $192.168.0.0/16$, which are not routable across the public Internet.

Network Address Translation (NAT)

A technology deployed on border routers that translates private IPv4 addresses into a public IPv4 address, permitting internal hosts to access public Internet services.

Address Resolution Protocol (ARP)

A Layer 2/Layer 3 mapping protocol that resolves a known IPv4 destination address to its associated hardware MAC address on a local network segment using broadcast requests and unicast replies.

Broadcast Domain

The logical segment of a network within which any broadcast frame sent by a host is received and processed by every other device; it is bounded and terminated by routers.

Unicast

A one-to-one communication mode where an individual sender transmits packets to a single designated recipient destination address.

Multicast

A one-to-group delivery mechanism using destination addresses spanning from $224.0.0.0$ to $239.255.255.255$, delivering traffic exclusively to subscribed member hosts.

Basic Service Set (BSS)

A fundamental building block of an infrastructure wireless network consisting of a single Wireless Access Point (WAP) serving wireless client stations in a defined coverage area.

Extended Service Set (ESS)

A wireless topology formed by connecting two or more Basic Service Sets together through a wired distribution system, enabling seamless roaming under a common SSID.

Independent Basic Service Set (IBSS)

A decentralized wireless ad-hoc network mode where two or more client stations communicate directly in a peer-to-peer fashion without a central access point.

Service Set Identifier (SSID)

A human-readable text name configured on a wireless access point to identify a specific Wi-Fi network to client stations.

CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)

A media access control protocol used in $802.11$ wireless networks where stations verify the medium is silent and utilize RTS/CTS handshakes with timers to prevent collisions caused by issues like the hidden station problem.

Network Allocation Vector (NAV)

A timer maintained by $802.11$ stations based on the Duration field in frames, indicating how long the RF channel will remain reserved and preventing other stations from transmitting.

MIMO (Multiple Input, Multiple Output)

A wireless antenna technology that uses multiple antennas at both transmitter and receiver to simultaneously transmit and receive multiple spatial streams of data.

OFDMA (Orthogonal Frequency-Division Multiple Access)

A digital modulation method implemented in Wi-Fi 6 ($802.11\text{ax}$) that subdivides radio channels into sub-carriers to allocate bandwidth to multiple users at the same time.

RADIUS

A centralized server protocol that manages user authentication, authorization, and accounting, functioning alongside a Network Access Server (NAS) and $802.1\text{X}$ client supplicants.

WPA3

The latest Wi-Fi security standard that implements Simultaneous Authentication of Equals (SAE) to deliver robust key exchange and defend against offline dictionary attacks.

IEEE 802.3

The open international technical standard developed by the IEEE that defines physical layer cabling, signaling, and data link layer specifications for wired Ethernet networks.

Frame Check Sequence (FCS)

A $4\text{-byte}$ field located at the end of an Ethernet frame containing a Cyclic Redundancy Check (CRC) value computed by the sender to enable bit-level error detection by the receiver.

Preamble

An $8\text{-byte}$ field prepended to an Ethernet transmission consisting of $7\text{ bytes}$ of alternating $1\text{s}$ and $0\text{s}$ followed by a $1\text{-byte}$ Start Frame Delimiter (SFD) to synchronize receiver clock timing.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection)

An access method used in half-duplex Ethernet where nodes listen before transmitting, detect collisions through a voltage spike on the medium, halt transmission, and back off for a random interval.

10BASE-T

An IEEE $802.3$ standard specifying $10\,\text{Mbps}$ baseband Ethernet transmission over Category 3 or higher unshielded twisted-pair (UTP) cabling up to $100\,\text{meters}$, terminating with RJ-45 connectors.

10BASE-FL

A fiber-optic Ethernet standard specifying $10\,\text{Mbps}$ baseband transmission over multimode fiber ($62.5/125\,\mu\text{m}$) with ST or SC connectors, extending transmission distance up to $2000\,\text{meters}$.

Crossover Cable

An Ethernet cable wired with T568A on one end and T568B on the other to swap transmit and receive pairs (pins 1 and 2 crossed with pins 3 and 6), used to directly connect like devices.

Spanning Tree Protocol (STP)

A network protocol running on Layer 2 switches that prevents switching loops by monitoring network topologies and dynamically placing redundant paths into a blocking state.

Manchester Encoding

A digital line encoding scheme utilized in $10\,\text{Mbps}$ Ethernet where bit values are defined by transitions mid-bit period: high-to-low represents a binary $0$, and low-to-high represents a binary $1$.

Coaxial Connectors

Physical hardware terminations used with coaxial cable; primary standard types include BNC (bayonet style), N-type (threaded threaded commercial/outdoor), and F-type (screw-on residential cable television/internet).

Single-Mode Fiber (SMF)

A thin optical fiber featuring a $9\,\mu\text{m}$ glass core that propagates a single straight ray of laser light with low attenuation, suited for long-haul networks spanning hundreds of kilometers.

Multimode Fiber (MMF)

An optical fiber with a $50\text{--}62.5\,\mu\text{m}$ core that supports multiple light angles emitted from low-cost LEDs, supporting bandwidths up to $10\,\text{Gbps}$ over LAN distances up to $550\,\text{meters}$.

Goodput

The actual rate of usable application payload data delivered successfully to a destination over time, calculated as throughput minus protocol encapsulation headers, acknowledgments, and retransmissions.

Throughput

The empirical measurement of total bits moving across a physical medium over a specified time interval, typically lower than rated bandwidth due to traffic congestion and device delays.

Crosstalk

The unwanted signal degradation caused when electromagnetic or magnetic fields leaking from one copper wire pair bleed into and interfere with an adjacent pair.

Encapsulation

The top-down protocol process wherein data produced by an upper-layer application is systematically enclosed inside lower-layer protocol data units by appending protocol-specific headers and trailers.

De-encapsulation

The bottom-up process executed by a receiving host where each successive layer strips off its corresponding header and trailer to deliver the unmodified payload data to the next upper layer.

Transmission Control Protocol (TCP)

A connection-oriented Layer 4 transport protocol that guarantees reliable, ordered byte-stream delivery through connection setup, sequence numbers, acknowledgments, and retransmission of lost segments.

User Datagram Protocol (UDP)

A lightweight, connectionless Layer 4 protocol that delivers datagrams with minimal overhead and no connection handshakes, sequence tracking, or retransmission mechanisms.

MAC Address

A permanent, factory-assigned $48\text{-bit}$ ($6\text{-byte}$) physical hardware identifier embedded in a NIC, represented as 12 hexadecimal digits and used for local Layer 2 frame delivery.

Hexadecimal Number System

A base-16 numbering system utilizing numerals $0\text{--}9$ and letters $\text{A--F}$, where each single hexadecimal digit represents a grouping of exactly four binary bits.