Network + 1.0 - 1.2

OSI

Open Systems Interconnection

What is the Open Systems Interconnection (OSI) model?

a framework used to understand network interations in seven layers.

What are the seven layers?

Layer 1 - Physical

Layer 2 - Data Link

Layer 3 - Network

Layer 4 - Transport

Layer 5- Session

Layer 6 - Presentation

Layer 7 - Application

Hosts

Any device with an IP address

Server

computer or systems that provides resources, data, services, or programs to other computers, known as clients, over a network.

Workstation

high performance computer designed for techinical or scientific applications used by 1 person at a time

Client Machine

computer or device that access services, appication, or resoures provide by a server over a network

Network Devices

allows servers, workstations, client computer to connect to share resources such as firewalls, routers, switches, or applications

LAN (Local Area Network)

small area such as home, office, or building. Typically used for sharing resources such as files and printers

WAN (Wide Area Network)

Large Gerographical area often a country or continet.

Example: Internet

MAN (Metropolitation Area Network)

covers a larger area then a LAN but small than a WAN, such as city.

CAN (Campus Area Network)

type of network that interconnects multiple local networks within limited geographical areas, such as universities, coporate campus, or large industrial complex

PAN (Personal Area Network)

small area usually in a single room.

Example: Bluetooth

Peer to Peer Network

each device can act as both as client and server, allowing direct sharing of resources, data, and services among all connected devices without a central server

Client server Network

a network architecture where multiple client devices connect to a central server to access shared resources, services, and application

How does client server network operates?

A client sends the requests for resources or services to a server, and the server processes those requests and sends back the requested datat or service.

P2P (Point to Point)

direct connection between two networking devices, using a single cable or wireless link.

Mesh

each host is connected to every other host, creating a network without no central connecting point

Star/Hub & Spoke

all nodes are connected to a central node such as hub/switch/wireless access point

Hybrid

combines 2 or more different topologies to a form a resultant topology that leverages the advantages and migrates the disadvantages for constituent topologies.

Physical (L1)

Function: Transmits raw bits

Examples: cables, switches, and electrical signals or light pulses that carries data

Data Link (L2)

Function: Frames data, handles MAC addressing, errors

Examples: MAC addresses, switches (layer2), LLC

Network(L3)

Function: Routes packets between devices

Examples: IP addresses, routers, ICMP

Transport (L4)

Function: Ensures reliable delivery, sequencing, error checking

Example: TCP/UDP, ports, ACKs

Session (L5)

Function: Manages sessions/connections between applications

Example: Opening/closing sessions, API sessions

Presentation (L6)

Function: Formats, encrypts, or compresses data

Example: Encryption (SSL/TLS), data encoding

Application (L7)

End user services (HTTP, FTP, email)

Hybrid

combines 2 or more different topologies to a form a resultant topology that leverages the advantages and migrates the disadvantages for constituent topologies.

Router

Directs data packets between different networks based on IP addresses

Layer 2 Switch

Network devices that operates at the Data Link layer on the OSI mode and fowards frames based on MAC addresses

Layer 3 Capable Switch

A multilayer switch that operates at both the Data Link and Network layers and can route traffic between VLANs using IP addresses.

Firewall

A network security device that monitors and controls incoming and outgoing network traffic based on a set of rules.

IPS Device

Actively bloakc or prevent activities based on devted anomalies, signatures, and policies

IDS Device

Passively monitor and alerts system administrators of suspicious activity

Load Balancer

Distributes incoming network traffic across multiple servers to ensure no single server becomes overwhelmed

Proxy Server

An intermediary server that sits between a client and the internet, forwarding client requests and responses.

Network-Attached Storage (NAS)

File storage device connected to a network, allowing multiple users and client devices to retrieve and store data from a centralized location

Storage Area Network (SAN)

High-speed network that provides access to consolidates, block-level data storage

Access Point (AP)

Networking devices that allow wireless devices to connect to a wired network using Wi-Fi or related standards.

Wireless LAN Controller (WLC)

Manages wireless access points in a network, centralizing control of the wireless LAN (WLAN)

Content Delivery Network (CDN)

Globallly distributed network of proxy servers and data centers designed to deliver internet content rapidly to users

Virtual Private Network (VPN)

safe and encryptewd connection over a less secure network, such as the internet

Quality of Service (QoS)

A set of technologies and policies used to manage and prioritize network traffic to ensure the performance of critical applications and services.

Time to Live (TTL)

field in the header of IP packets that specifies the maximum time or number of hops a packets is allowed to traverse