Networks Flashcards
ASCII
American Standard Code for Information Interchange
the type of code that tells your keys what is being typed, offering 128 characters, with one bit per character
Application Software
enables the user to perform a specific task, for example a word processer allows storage of text and simple images and web browser displays web pages
Attenuation
the loss of signal strength when transmitting signals
Batch Processing
where large amounts of information are processed all at once
Bridge
a computer networking device that creates a single aggregate network from multiple communication networks or network segments
Brouter
does the work of the bridge and router
Buffer
a temporary memory area, which holds the data for the output hardware
Character
single character, eg a s d f g h j k l ; 1 5 6
Character Set
a defined list of characters recognised by computer hardware and software
Connectivity
methods for connecting devices to each other in order to transfer data, including cabling and wireless
Data
a set of raw facts or figures with no apparent reason
Device Drivers
manages the connection with a peripheral device, handles the different requests between a computer and a device, puts a device into sleep mode if it is idle for a specified time, can control multiple peripherals using the same protocol
Disk Defragmentation
a process the reduces the amount of fragmentation on a hard drive
Domain Name System
a distributed database that matches IP addresses to computer system resources, for example, to give a domain name google instead of 173.194.34.191
Domain Space Hierarchical Structure
a way of representing the structure of URLs
Dynamic Host Configuration Protocol Server
a server that allocates IP addresses
EBCDIC
Extended Binary Coded Decimal Interchange Code
a method of character encoding that uses 8 bits instead of 7 bits like ASCII, and so is less efficient and isn’t used as much
Fibre Optic Cables
cables made of many optical fibres in plastic casing, transferring data signals in forms of light
Full Duplex
allows more than one person to transmit data at one time, unlike half duplex
Gateway
a piece of networking hardware used in telecommunications networks that allows data to follow from one discreet network to another
Half Duplex
same as walky-talkies, allows only one person to transmit data at a single time, despite all people bieng able to transmit data
Hub
node that broadcasts to every computer or ethernet-based device connected to it
Information
data which has been processed and given meaning
Integer
whole number
Interrupt
where a signal is sent that temporarily halts a program
Internet
a global computer network providing information and communication facilities, consisting of many networks
IP Address
Internet Protocol Address
an address allocated to a computer system on a network, used to uniquely identify systems on a network, allowing communication between them
Kernels
the control centre of the operating system that deals with hardware operations
LAN
Local Area Network
used for small, localised networks, such as in homes and schools
Lossless Data
a way of compressing data without removing parts, such as ZIP files
Lossy Data
a way of compressing data by removing parts, permanently changing it
compression ratio = original file size / compressed file size
MAC Address
Media Access Control Address
a 12-digit hexadecimal number that is most often displayed with a colon or hyphen separating every two digits to make it easier to read
Memory Management
the operating system allocates memory to each process, often using defragmentation, paging and segmentation
Multiprogramming
when an operating system is multi-tasking and running several programs at once
Network Interface Card
provides the computer with a connection to the network
Network Protocols
allows computers on a network to communicate
Wi-Fi
wireless, two common standards are Bluetooth and 801.11
TCP
Transmission Control Protocol
popular communication protocol which is used for communicating over a network and divides any messages into a series of packets that are sent from source to destination where it gets reassembled
IP
Internet Protocol
an addressing protocol that is often combined with TCP to use with a series of packets
HTTP
Hypertext Transfer Protocol
allows webpages to be shared
HTTPS
Hypertext Transfer Protocol Secure
allows webpages to be shared securely
POP3
Post Office Protocol 3
most commonly used for receiving e-mails over the internet
SMTP
Single Mail Transfer Protocol
allows transmission of e-mails on a computer network
IMAP
Internet Message Access Protocol
transfers e-mails between computer systems via the internet, generally used for retrieval and storage
FTP
File Transfer Protocol
used for uploading files
Node
any physical device connected to a network that is able to send, receive or forward information, such as computers, servers, routers and switches
Octet
two groups of digits in a MAC address
OSI Model
Open Systems Interconnection Model
has seven layers, explains how data is transferred
Applications Layer
first part of the OSI model, tells the computer how the data is going to be used
Presentation Layer
second part of the OSI model, tells the computer how the data is going to be read
Session Layer
third part of the OSI model, says how the data is to be exchanged (half or full duplex)
Transport Layer
fourth part of the OSI model, says how data is going to be transported, broken up, and then put back together
Network Layer
fifth part of the OSI model, says how things are to be sent across eg traffic control, internet protocol, keeps addresses of different computers to each computer, decides which route the data takes
Data Link Layer
sixth part of the OSI model, says how the data will be carried, e.g. how quickly
Physical Layer
seventh part of the OSI model, the raw bit that streams over a physical medium, eg Bluetooth, Ethernet, USB
Operating System
software that runs in the background of a computer system and acts as an interface between the user and the important applications, its five functions being human computer interface, memory management, multiprogramming, file management and real-time processing
Packet
a collection of data that is transmitted over a packet-switched network. These are provided to a network for delivery to a specified location. Each packet of data is redirected by a computer system along the network until it arrives at its destination. Data may be split into several packets. When all packets have arrived, the data is a reassembled. Packets include source address, destination address, information which enables data to be reassembled in its original form, tracking information, the data itself and a checksum
Source Address
part of a packet, explains where the data has come from
Destination Address
part of a packet, explains where the data needs to go
Checksum
checks the data has not been corrupted, usually an extra 1 or 0
Packet Switching
the process of delivering packets from one computer system to another, such as a switch or router
Pages
equally-sized blocks that memory can be split into, which can be allocated to processes
Printer Spooling
a small application that provides a waiting system until the data can catch up
Protocol
an agreed-upon format that allows two devices to communicate, protcols may include handshaking, how the sending device will indicate it has finished sending, how the receiving device will indicate it has finished receiving, the type of error checking to be used, agreement on the data compression method to be used
Handshaking
where two devices establish their readiness to communicate
Protocol Stacks
a set of network protocol layers that work together
Real Number
number with or without a fraction
Real Time Processing
where something is processed as you do it, such as when you are typing into a word document
Float
number with a fraction
Repeater
a device which reduces problems caused by signal attenuation
Router
a networking device that forwards data packets between computer networks and performs the traffic directing functions on the internet.
Routing
the name given to the method of selecting paths along which packets are sent on a computer network
Static Routing
where data travels to its destination along a pre-set path, straightforward to implement, but if lots of data is using that path, transmission can take longer
Dynamic Routing
where data packets can take different routes. This is more complex to implement, but means congested parts of the network can be avoided, meaning data transmission can be completed more quickly
Routing Table
used to store corresponding IP addresses with MAC addresses, and is stored and updated as necessary
Runnable Program
a program that cannot be run at the current time as there is not enough memory
Running Program
a program running at the current time
Scheduling
determines how processes are run and swapped, where the operating system may choose the shortest job first or the one with the longest waiting time first, is managed by the operating system and is very important for efficient and fair processing of all processes
Searching Algorithms
a computer uses searching algorithms to search for a value in a given list
Binary Search
a more efficient way of soring that only works on sorted lists which starts by finding the middle item and comparing it to the value it is searching for; if the middle value is smaller than the value it is searching for then the first half of the list is removed, including the middle value. If the new middle value is larger than the value it is searching for then the top half of the list is removed, including the middle value. This process is repeated until the value is found
Linear Search
goes through each item in an algorithm one by one until it finds the one it is looking for, then it stops the search after potentially going through every item in the list
Segmentation
splitting memory and allocating it to processes
Sorting Algorithm
something a computer uses to set unordered lists and values
Bubble Sort
works by working through a list, comparing pairs and values and swapping them if they are in the wrong order. Is simple to implement but is very inefficient.
Merge Sort
works by splitting the lists into individual values and gradually merging them to form bigger lists until they are all in one sorted list. Is one of the most efficient when used with both big and small lists.
Standards
manufactured following sets of rules, agreed amounts of data loss
String
more than one character, can be shortened to str
Switch
similar to a hub, but is able to tell which device it needs to broadcast data to
Topology
a way in which network devices are arranged
Bus Topology
in which computers are arranged in a line, with wires connecting them to each other, also known as a daisy chain
Hybrid Topology
a combination between the different topologies, in which each devices is connected in at least two ways to other devices
Ring Topology
where devices are arranged in a ring, with wires connecting them to each other
Star Topology
where devices are each individually connected to a central hub or switch
Unicode
a sixteen-bit character set with 65536 characters available, allowing it enough characters for any writing system. This is the standard character set and is used by all major web browsers and applications. It uses more storage than ASCII, with two bits per character.
Utility
a program that is installed in a system alongside the operating system to perform a limited range of functions
Waiting Program
a program that could potentially run at the current time as there is enough memory but isn’t being run
WAN
Wide Area Network
connects devices but extends across a large geographical distance such as a leased telecommunications network
Web Browser
an application used to access websites and render their HTML code to allow viewing
WLAN
Wireless Local Area Network
WAP
Wireless Access Point
an access point is a device that creates a wireless local area network, normally wireless
