Communication and networking Flashcards
Network
group of devices connected together to communicate with each other and share resources
LAN
Local Area Network - network that connects devices that are located in a small geographical area
WAN
Wide Area Network - when devices are connected across a wider geographical area
Physical bus topology
consists of a single, central cable (called backbone) that connects all devices
Star topology
uses a central device, such as a hub or switch, to interconnect devices
MAC address
Media Access Control address - hardware address that uniquely identifies each node on a network
Ethernet
a family of related protocols rather than a single protocol
Physical topology
The physical arrangement of connections that describes a network’s physical layout and shape
Logical topology
describes the data-flow patterns in a network
Asynchronous transmission
data transmitted when it is ready to be sent without being synchronised to a clock signal - instead uses start and stop bits
Serial transmission
data is transmitted one bit at a time down a single wire
Parallel transmission
transmission of several bits at a time using multiple parallel wires
Bit rate
number of bits transmitted per second
Baud rate
rate at which the signal changes
Bandwidth
maximum rate of data transfer across a communication channel
Latency
delay from the time a signal is sent to the time the signal is received
Synchronous transmission
data transmission method in which a digital signal is synchronised with a clock pulse
Protocol
set of rules that determine communication between devices
CSMA/CA
Carrier Sense Multiple Access/Collision Avoidance - a protocol for carrier transmission in wireless LANs
SSID
Service Set Identifier- sequence of characters that uniquely names a wireless LAN
Internet
a global network of interconnected networks that communicate using a common set of standards and protocols
Uniform Resource Locator(s) (URL)
the full address for an Internet resource
Internet registrars
they ensure that a particular domain name is only used by one organisation, + hold records of all existing website names
Internet registries
(five) global organisations responsible for the allocation of IP addresses
Domain name
identifies the area or domain that an internet resource resides in
Fully Qualified Domain Names (FQDN)
the complete address of an internet host/server - includes host server name e.g. www, mail or ftp (web, mail, or ftp server)
Router
networking device that forwards data packets between computer networks
Packet switching
transfer of small ‘packets’ of data across various networks - allows for faster/more efficient data transfer
Routing tables
set of rules in routers used to decide where data packets will be directed
Firewall
a security checkpoint designed to prevent unauthorised access between two networks - monitors both incoming and outgoing traffic
Stateful inspection
continuously monitoring incoming and outgoing traffic after connection established - analyses packet types by looking inside payload and checks for suspicious activity
Connection table
keeps track of all the conversations going on between the trusted and untrusted networks
Proxy server
sits between the client devices and firewalls, providing anonymity to clients by keeping their true IP addresses hidden
Symmetric encryption
uses same key for both encryption and decryption
Asymmetric encryption
uses a related set of keys: one private and one public
Authentication
action of verifying the identity of a user or process
Digital signature
a mathematical scheme for verifying the authenticity of digital messages or documents - guarantees integrity of a message
Digital certificate
an electronic document that authenticates a message sender or website
IP address
a unique numerical address that identifies a host computer or network node trying to communicate over IP on a network
Edge router
point where router connects to the internet/where an internet connection is established
Subnet mask
a 32-bit number created by setting host bits to all 0s and network bits to all 1s
Subnet
subdivisions of networks that are treated logically as separate networks - connected by routers
Non-routable addresses
cannot be moved on by internet routers
Dynamic Host Configuration Protocol (DHCP)
dynamically assigns private (non-routable) IP addresses + other configuration options to devices in a network
Post forwarding
technique that allows remote computers to connect to a specific computer/service within a private LAN
Network Access Device (NAD)
a combined device that provides a modem and router to connect to internet, as well as an Ethernet and WAPs so that multiple devices on LAN can share connection
TCP/IP
a set of rules used to format a message so it can be sent over a network - each layer provides specific function within transmission of message
Encapsulation
taking data from layer above in protocol stack and placing it in an envelope, writing some additional info on envelope then passing it to layer below
Transmission Control Protocol (TCP)
keeps track of each generated segment and assigns sequence numbers (added to segment header)
User Datagram Protocol (UDP)
used across internet for especially time-sensitive transmissions such as video playback or DNS lookups
HTTP Secure (HTTPS)
encrypts data exchanged between client and server
Post Office Protocol (POP3)
downloads emails onto client device and deletes them from server
Internet Message Access Protocol (IMAP)
creates copies of email(s) on a local client device and synchronises any deletion on both client and server
Simple Mail Transfer Protocol (SMTP)
transfers emails from client device to linked mail server
Application Programming Interface (API)
a set of functions and protocols that clients can use
Client-server model
paradigm where providers of resources are designated as servers and resource requesters are designated as clients
Sandbox
an environment that isolates code so that it can’t have access to, or affect, other parts of the system
Thin-client
a device that has limited main memory, limited secondary storage and only basic processing capabilities
De jure standards
standards that are regulated by official bodies
De facto standards
standards that arise through popular use but are not managed or regulated
JavaScript Object Notation (JSON)
lightweight format for storing and transporting data - often used when data is sent from a server to a webpage
Extensible Markup Language (XML)
used for storing, transmitting and reconstructing arbitrary data
Schema
a type of metadata that specifies, and therefore constrains the structure of the XML file
CRUD
Create, Retrieve, Update, Delete - represents the four basic operations relating to data stored in files/databases
REST
Representational State Transfer - an architecture style for developing web services that specify the use of distinct HTTPs for all four CRUD operations
Websocket
protocol that is an open standard for developing real-time web applications
Thick-client
opposite of thin-client - high performance and storage
