ap networking

intermediate node

performs a forwarding function

end systems

systems that send and receive data traffic

client server

network where most nodes act as a client

peer-to-peer network

network where each host acts as a client and a server

server

makes applications and resources available to other hosts

clients

consumes the services provided by servers

local area network (LAN)

network confined to one geographical location

small office/home office (SOHO)

a small business-oriented network

enterprise LAN

a larger network with thousands of servers and clients

datacenter

a network that hosts only servers and storage

wide area network (WAN)

a network of networks, connects networks globally

topology

physical or logical structure of a network

point-to-point link

simple connection between two nodes

half-duplex

a point-to-point link that can transfer data both ways but not at the same time

full-duplex

a point-to-point link that can transfer data both ways at the same time

star topology

a network structure where all end nodes are connected to a central appliance

hub-and-spoke topology

same as star topology but for WAN

mesh topology

a network structure where each device has a point-to-point link with every other device

bus topology

one of two legacy topologies that consists of a trunk cable and devices in a single line

ring topology

the other legacy topology, a network structure that forms a ring

data addressing

describing where data should go

data encapsulation

describing how data should be packages for transmission(adding headers)

osi layer 1

the physical layer, responsible for transmission and receipt of signals that represents bits of data

components at osi layer 1

repeaters, hubs, media converters, and trancievers

osi layer 2

the data link layer, responsible for transferring data between nodes, uses frames

components at osi layer 2

network adapter or network interface card(NIC), bridge, switch, wireless access point(AP), mac address, VLAN

osi layer 3

the network layer, responsible for moving data around network of networks by giving each packet a destination network addresss

components at osi layer 3

router, basic firewalls, access control list(ACL), datagram

osi layer 4

the transport layer, also known as the end-to-end, is responsible for transferring data by assigning each application a port number with segments

components at osi layer 4

multilayer switches, advanced firewalls and intrusion detection systems(IDS)

osi layer 5

the session layer, responsible for starting, managing, and ending connections

osi layer 6

the presentation layer, responsible for transforming data to the format required for an application

osi layer 7

the application layer, responsible for providing an interface for software programs

components at osi layers 6 & 7

application protocols (web, email, file transfer, etc)

osi layer 1 functions

RJ45 ports implement a local cabled network, connect to ISP(internet service provider)

osi layer 2 functions

RJ45 jacks connect to ethernet switch

osi layer 3 functions

makes decisions between local private network and public internet with IP addresses

osi layer 4 functions

functions also as security

network troubleshooting methodology

steps for solving a problem in a network

ntm step 1

identify the problem

ntm step 2

establish a theory of probable cause

ntm step 3

test the theory to determine the cause

ntm step 4

establish a plan of action and identify possible effects

ntm step 5

implement a solution or escalate if necessary

ntm step 6

verify system functionality

ntm step 7

document findings

network data transfer

modulating the properties of a transmission medium to encode a signal

the three ethernet standards

the speed or rate in mega or gigabits per second, the signal mode, and a designator

twisted pair copper cable

insulated copper wires twisted around each other to cancel out electro-magnetic interface(EMI), used for telephone systems and data networks, can be shielded (STP) or unshielded (UTP)

media access control (MAC)

a physical identifier for hardware used for local network traffic

collision domain

network segment where nodes are attached to the same shared access media

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

a set of protocols that reduce the possibility of data collisions

collision

a state when a signal is present on an interfaces transmit and receives lines at the same time

fast ethernet

100 Mbps(100BASE-TX), implemented with a hub,

fiber optic cable

a cable that has a center glass surrounded by multiple layers of protective materials, used to send information at the speed of light, high bandwidth than twisted pair

-T

twisted cable

-F

fiber optic cable

gigabit ethernet

1000 Mbps(1 Gbps) 1000BASE-T, implemented with switches, max distance 100 meters(328 ft)

auto negotiation

allows devices to automatically determine best duplex and speed

baseband transmission

used for short distance, digital, and bidirectional communication

broadband transmission

used for long distance, analog, and unidirectional communication

cat (cables)

related to twisted pairs, cat (category) defines what bandwidth it should support, with higher numbers representing better support

crosstalk

phenomenon where one pair causes interface due to proximity

interface

point of communication between different components

solid cabling

single thick wire used for cables that run behind walls or through ducts

stranded cabling

thin, filament wires twisted around each other used to make flexible patch cords for connection computers to wall and switch ports

shielded vs unshielded cables

shielded are more rigid and expensive, while unshielded is more cost-effective and flexible

registered jack (RJ)

series of jack/plug types used for twisted-pair cabling such as RJ45 or RJ11

RJ45 connectors

used with 4-pair copper cables

RJ11 connectors

used with 2-pair copper cables

plenun space

a void in a building designed to carry heating, ventilation, and air conditioning (HVAC) systems

riser cable

a cable that passes through two floors

coaxial cable (coax)

a cable with a single copper conductor in the middle inside a layer of insulation, a braided metal shield, and an exterior plastic sheath

twinaxial cable (twinax)

similar to a coaxial but with two inner conductors

screen cabling (ScTP)

uses a thin outer foil shield around all pairs

central processing unit (CPU)

aka processor or “the brain”, processes data, manages input/output, and executes instructions from software or hardware

random access memory (RAM)

type of storage that temporarily holds data for immediate operations

RAM importance

with insufficient ram, systems can run slowly and occasionally crash

solid state drives (SSD)

a high-speed, non-volatile storage device with no moving parts

hard disk drives (HDD)

a low-cost, electro-magnetic storage device with moving parts(spinning platters)

HDD vs SSD

SSDs are significantly faster, more durable, and use flash memory to store data. HDD use mechanical spinning platters and are generally cheaper

firmware

a software that manages hardware components

basic input/output system (BIOS)

essential firmware stored on a motherboard chip responsible for power on/off devices and ensuring all components function together before loading OS

unified extensible firmware interface (UEFI)

modern software standard that replaces BIOS to act as a middleman between a computer’s firmware and operating system

operating system

a software that interfaces between the user and the hardware, responsible for managing resources and performing system tasks (Windows, macOS, Linux..)

application software

software that performs a specific function not directly related to the computer system (internet browsers, games, word processors…)

driver

a software that allows a device to communicate with a computer’s operating system

virtual instance/virtual machine

an emulation of a physical computer running an operating systems and applications

file system

a logical structure that names and stores files on a computer system, managed by the operating system

directories

an organizational structure that holds multiple files or other directories

dynamic host configuration protocol (DHCP)

a network management protocol that automatically assign IP addresses and configuration settings to devices

port #21

file transfer protocol (FTP)

port #22

secure shell (SSH)

port #25

simple mail transfer protocol (SMTP)

port #53

domain name system (DNS)

port #80/443

hypertext transfer protocol (HTTP/HTTPS)

graphic user interface (GUI)

virtual system that allows users to interact with icons, menus, and windows

comand line interface

text-based user interface used to interact with computer operating system

~

home directory of the current user

ls

the list command, displays contents of the current directory