CCNA Networking: IPv4 Addressing, Subnetting, Routing, and Cabling

Vocabulary practice flashcards covering CCNA networking fundamentals: IPv4 classes, public and private addressing, FLSM and VLSM subnetting principles, router internal architecture, Cisco IOS configuration commands, and network cabling standards.

Public IP

A paid IP address obtained from an Internet Service Provider (ISP) that allows devices to connect to and access the global internet.

Private IP

A free IP address used internally by anyone in the world to connect and network local devices together within an internal network.

Class A Private IP Range

The private IPv4 address block spanning from $10.0.0.0$ to $10.255.255.255$, representing $1$ network.

Class B Private IP Range

The private IPv4 address block spanning from $172.16.0.0$ to $172.31.255.255$, providing $16$ networks.

Class C Private IP Range

The private IPv4 address block spanning from $192.168.0.0$ to $192.168.255.255$, providing $256$ networks.

IPv4 (Internet Protocol Version 4)

A 32-bit logical device identifier consisting of 4 octets separated by dots, where each octet contains numeric values ranging from $0$ to $255$.

Class A IPv4 Range

An IPv4 class where the first octet ranges from $1$ to $126$ with an $N.H.H.H$ structure, containing $126$ networks and $16,777,216$ hosts ($256 \times 256 \times 256$) per network.

Class B IPv4 Range

An IPv4 class where the first octet ranges from $128$ to $191$ with an $N.N.H.H$ structure, containing $16,384$ networks ($64 \times 256$) and $65,536$ hosts ($256 \times 256$) per network.

Class C IPv4 Range

An IPv4 class where the first octet ranges from $192$ to $223$ with an $N.N.N.H$ structure, containing $2,097,152$ networks ($32 \times 256 \times 256$) and $256$ hosts per network.

Loopback Address

The IPv4 block $127.X.X.X$, reserved for testing the internal network interface of the local host.

Class D IPv4 Range

The IPv4 address range from $224$ to $239$, reserved for Multicast operations including routing protocols such as RIP ($224.0.0.9$), EIGRP ($224.0.0.10$), and OSPF ($224.0.0.5$ and $224.0.0.6$).

Class E IPv4 Range

The IPv4 address range from $240$ to $255$, reserved exclusively for scientific research and experimental purposes.

Unicast

A one-to-one ($1 \text{ to } 1$) network communication method where data packets are sent from a single sender to a single specific receiving device.

Multicast

A one-to-group ($1 \text{ to group}$) network communication method where data packets are transmitted from one sender to a designated group of devices.

Broadcast

A one-to-all ($1 \text{ to all}$) network communication method where data is sent from a single sender to all connected devices across the entire network.

Bit

The fundamental binary transmission unit across a computer network, representing a single binary state of either $0$ or $1$.

Byte

The primary unit of data storage in computer systems, composed of $8$ bits.

Subnet Mask

A 4-octet parameter separated by dots with values from $0$ to $255$ used to divide large networks into smaller subnets or confirm the number of allocated IP addresses.

Fixed Length Subnet Mask (FLSM)

The default subnet mask specific to each standard IP class (Class A: $255.0.0.0$, Class B: $255.255.0.0$, Class C: $255.255.255.0$), indicating the base allocation of network and host bits.

Variable Length Subnet Mask (VLSM)

A subnetting technique that subdivides a single network into multiple smaller subnets of varying sizes to optimize IP address efficiency.

Network ID (NID)

The first IP address within any given network or subnet; it identifies the subnet itself and cannot be assigned to an end device.

Broadcast ID (BC)

The last IP address within any given network or subnet; it is reserved for sending broadcast transmissions to all devices in that subnet and cannot be assigned to an end host.

Subnetting Rule 1 (Available Subnets)

The rule calculating the total number of subnets as $2$ raised to the power of the number of binary 1s present in the working octet ($2^n$).

Subnetting Rule 2 (IPs per Subnet)

The rule calculating available IPs per subnet in Class C as $2$ raised to the power of binary 0s in the working octet, or the step/block size between subnets in Class A and Class B.

Subnetting Rule 3 (Usable Host Formula)

The mathematical formula $2^{\text{total zeros in subnet mask}} - 2$ used to determine the exact number of usable host addresses (PCs) available in each subnet.

Bitwise AND Operation (Subnetting)

The logical rule used to find the Network ID by performing a bitwise logical AND comparison between the host IP address and its subnet mask.

Router

A Layer 3 device that interconnects different IP networks, routes data packets between them, aggregates small networks into a larger one, and connects local networks to the internet.

Routing Table

An internal table built by a router (taking $20$ to $50$ seconds upon booting its operating system) that stores all connected and learned destination networks.

Connected Network

A local network that is directly connected to the router's physical interfaces and configured with a local interface IP address.

Destination Network

A remote network not directly attached to the router, which the router must learn about through static configuration or dynamic routing protocols.

Static Routing Protocol

A manual routing approach where network administrators explicitly program and define the routes to unknown/remote networks into the router.

Dynamic Routing Protocol

An automated routing method where routers automatically learn remote networks and calculate best paths by exchanging routing updates with other routers.

Router Power Supply

The internal hardware component responsible for supplying electrical power to the router, serving as the first and last line of defense against voltage spikes and drops.

Router RAM (Random Access Memory)

Volatile temporary memory in a router that loses its contents when power is disconnected, used to temporarily store operating buffers and packets during transmission and reception.

Power On Self Test (POST)

A hardware diagnostic check executed by the ROM upon startup to verify that all vital router components are fully functional before initializing the device.

NVRAM (Non-Volatile RAM)

Non-volatile memory that preserves its stored information even during power interruptions, used specifically to store the router's startup configuration.

Router Flash Memory

The permanent storage memory module inside the router where the Cisco Internetwork Operating System (Cisco IOS) is stored.

Console Port

A management interface labeled in sky blue located on the router exterior, used with a console cable to connect a computer for initial setup and device configuration.

Serial Port (DB60 / Smart Serial)

A legacy physical WAN interface available in DB60 or Smart Serial form factors, previously used to interconnect routers over slow-speed serial links.

show ip interface brief

A Cisco IOS command used in privilege mode to query the names, assigned IP addresses, and Layer 1/Layer 2 operational statuses of all router interfaces.

show ip route

A Cisco IOS command used to display all connected and destination networks currently recorded in the router's routing table.

show running-config

A Cisco IOS command used to view the active configuration currently executing in the router's volatile RAM.

no shutdown

A Cisco IOS interface configuration command executed to activate an interface and change its administrative state to 'up'.

clock rate 64000

A command configured on a router's serial DCE interface to set the line synchronization speed to $64,000\text{ bps}$.

no ip domain lookup

A Cisco IOS global configuration command used to permanently stop the router from mistranslating mistyped CLI inputs as domain names via DNS.

Unshielded Twisted Pair (UTP)

A copper networking cable composed of four pairs of twisted wires that lack electromagnetic shielding.

Shielded Twisted Pair (STP)

A copper networking cable composed of four pairs of twisted wires protected by external metallic shielding to mitigate electromagnetic interference.

Straight-Through Cable

An Ethernet cable where both ends share identical wire arrangements, used to connect dissimilar devices such as a Switch to a PC or a Switch to a Router.

Crossover Cable

An Ethernet cable where transmit and receive pairs are swapped on one side (pin 1 with pin 3, pin 2 with pin 6), used to connect similar devices such as Router to Router, PC to PC, Router to PC, or Switch to Switch.

Power Over Ethernet (PoE) Pinout

An Ethernet wiring arrangement where pins 1, 2, 3, and 6 carry data while pins 4, 5, 7, and 8 supply electrical power to connected devices.

Coaxial Cable (Coaxil)

A shielded cable comprising an outer plastic jacket, braided copper/tin/aluminum mesh, dielectric insulator, and a central solid copper core, commonly terminated with a BNC connector.

10BASE2

A thin coaxial cable standard (Thinnet) transmitting data at $10\text{ Mbit/s}$ with a maximum segment signal reach of up to $180\text{ meters}$.

10BASE5

A thick coaxial cable standard (Thicknet) transmitting data at $10\text{ Mbit/s}$ with a maximum segment signal reach of up to $500\text{ meters}$.

Single-Mode Fiber Optic (One Signal)

A long-distance optical cable with a core diameter of $9\,\mu m$ that transmits a single light signal up to $4\text{ km}$ or between cities and countries.

Multi-Mode Fiber Optic (Multi Signal)

A short-distance optical cable with a core diameter of $62\,\mu m$ that carries multiple light signals simultaneously across distances of $800\text{ meters}$ to $2\text{ km}$.