Important terms

  • TCP(Transmission Control Protocol), connection-oriented , "reliable" delivery , eg. loading a website

  • UDP (User Datagram Protocol) , connectionless ,"reliable" delivery , eg live-stream

  • IP address = which house

  • Port = which room

  • Non-ephemeral ports (0-1,023) = permanent port numbers , eg. 80 for web servers and port 443 for HTTPS

  • Ephemeral ports (1,024-65,535) = temporary port numbers (servers mostly use these)

Network devices

  • Router : A router routes traffic between IP subnets

  • Subnet : seperate larger network into smaller, manageable segments

  • Switch : Provides physical connections between network devices within a LAN

  • Patch panel : organise network cables , many desktops to one patch panel

  • PoE (Power over Ethernet) : for telephone , PoE

  • Hub (old , before switches) , inefficient

  • Type of internet connection technologies :

    • Cable: Uses coaxial cables (from TV) to provide internet

    • DSL (Digital Subscriber Line): Uses copper telephone lines for internet

    • Fiber: Uses fiber optic cables for high-speed internet

  • Gateway = Modem + Switch + Wifi Router

  • NIC (Network Interface Card)

Others

  • SDN (Software Defined Networking) : Provides an interface that allows users to manage and control all the network's control planes from a GUI( Abstracting the control plane from the data plane)

  • 802.11.ax = WIFI 6

  • RFID

  • NFC

  • 2.4 GHz vs 5GHz , their frequency channels (overlapping?)

  • DNS

  • DHCP

  • proxy

  • Load balancer

  • IPv4 vs IPv6

  • Subnet mask

  • Default gateway=ip address of router

  • DHCP process = DORA (Design,Offer,Request,Accept)

  • APIPA , when there is no DHCP server

  • DNS records (Each type of DNS record serves a specific purpose) under DNS configuration:

    • A : Maps a domain name to an IPv4 address.

    • AAAA : Maps a domain name to an IPv6 address

    • CNAME: Aliases one domain name to another

    • MX

  • Static DHCP assignment (by MAC address of device)

  • DHCP lease renewal

  • VLAN (Virtual LAN): Segments a physical network into multiple logical networks (Eg. Use 1 switch instead of 3 switches to make 3 LANs)

  • VPN (Virtual Private Network): Eg. Laptop with VPN software enabled -> VPN Concentrator (manages and secures multiple VPN connections) -> Corparate Network

Networking tools

  • Crimping

  • Cable tester (test the RJ45 after crimping)

  • Tone generator

  • loopback adapter : test connection

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