networks T5 Flashcards
what is a network?
two or more computers that are connected together for the purpose of communication
how are devices in a network connected?
they can be connected by a wired medium such as cables or wireless such as WiFi
what is a stand-alone?
a computer or device that is not connected to a network
what are the advantages of using networks?
file sharing - users can share files with other users
hardware sharing - users can share hardware, such as a printer
communication - users can communicate via email
roaming access - users can sign in to any computer on the network and gain access to their files
centralised maintenance - managers can apply software updates across a network
centralised security - antivirus software and firewalls can be implemented across a network to protect data
levels of access - different users can be given different access rights and this gives network managers the ability to restrict user access to certain files
what are the disadvantages of networks?
cost - additional equipment is needed to allow computers to communicate
management - networks require management by technical staff such as a network manager
spread of malware - viruses and other forms of malware can easily spread across a network
hacking - once a device is connected to another device it is possible that data may be accessed without the device owner’s permission
what is a LAN?
a local area network is a network that is geographically confined to one building or site
EXAMPLES: schools, universities
what is a WAN?
a wide area network is a network that is spread over a wide geographical area
EXAMPLES: banks
what is the internet?
a global network connecting millions of computers so huge international WAN
what is a PAN?
a personal area network is a network that is spread over a very small area and is used to connect personal devices such as a phone and laptop
to connect a device to a network, what hardware components are required?
a NIC (network interface controller)
a transmission medium (Wired or wireless)
a point to connect to such as a router, hub, switch or WAP
what does a NIC do?
it offers an interface port for a wired connection and a wireless NIC provides a radio transceiver for connecting wirelessly
what are switches?
network devices that record which computers are connected to which ports
when traffic is received the switch forwards the traffic to the intended recipient ONLY
what are routers?
a connection device that sends data signals across the internet
they collect knowledge of available routes to transmit data and then determine the most suitable one
what do transmission media do?
carry data signals from one computer to another
what is a fibre optic cable?
a cable that carries data transmitted as light
compare a twisted copper wire with a fibre optic cable?
fibre optics are more expensive to purchase and install
fibre optics have a faster transmission speed
fibre optic cables have a longer distance for communication (over 2 km)
how do WAPs work?
they use a radio transceiver to allow wireless connections to a network
it creates its own wireless network that devices can connect to
it sends wireless traffic to the main wired network
why are WAPs used?
used to extend the range of a wireless network
the WAP can either receive or transmit traffic to other WAPS
compare wired and wireless networks
wireless networks are cheaper to set up
wireless networks are simple to install but wired requires space and knowledge to install cables
wireless networks have a faster transmission speed
wireless networks have a smaller distance for communication 50 metres vs 2 km
wireless networks are less secure as the signal cannot be contained within a building and no physical connection is required to intercept data
what is a node?
any device connected to a network
what is a network topology?
the arrangement or pattern in which all nodes on a network are connected together
what is a bus topology?
a network layout where all nodes are connected along a linear link
what is a star topology?
a network where each node is connected to a central switch
how does a bus topology work?
all nodes in the network are connected directly to a central cable that runs up and down the network
data is send up and down the backbone until it reaches the correct node
what are the advantages of using a bus topology?
- it is easy to connect nodes to the network
- less cabling is needed compared to a star top. so it is cheaper to install
what are the disadvantages of bus topologies?
- the whole network fails if the backbone cable is broken
- terminators must be installed at each end of the backbone
- having one backbone increases the chances of data collision
how do star topologies work?
- all nodes are indirectly connected to each other through one or more switches
- the switch acts as a central point through which all communications are passed
what are the advantages of a star topology?
- each node is separately connected, therefore a failure of one node or its link does not affect any other nodes
- new nodes can be added to the network simply by connecting them to the switch
- star networks tend to have higher performance as a message is passed on to its intended node only
what are the disadvantages of star topologies?
- the whole network fails if the switch fails as no node can communicate
- a wired star topology requires lots of cable which can be expensive
what are protocols?
a set of rules for how messages are turned into data packets and sent across networks
what is IP addressing?
internet protocol - a set of rules for communicating over the internet
what is MAC addressing?
media access control - each unique piece of hardware on a network has a MAC address
what is the purpose/how does IP addressing work?
- when connected to a network each device is given a unique IP address
- when a node wants to send a message to another node, it uses the recipient node’s address as the destination
- a switch on the network knows where the node is routes the message accordingly
what is a static IP address?
an IP address that is always the same
what is a dynamic IP address?
a node is given a different address each time it connects to the network
why are static addresses used?
it makes it easy for network managers to known which device is which on a network
why are dynamic ip addresses used?
it allows more devices to connect than there are available addresses
what is MAC addressing?
a MAC address is a unique serial number assigned to each NIC
this allows a network to uniquely identify any device even if dynamic IP addressing is used
what is TCP/IP?
- transmission control protocol/internet protocol
- enables communication over the internet
what is HTTP/S?
- hypertext transfer protocol (secure)
- governs communication between a webserver and a client
- https includes secure encryption to allow transactions to be made over the internet
what is FTP?
- file transfer protocol
- governs the transmission of files across a network and the internet
what is UDP?
- user datagram protocol
- faster than TCP allows gaming or video calls over the internet
what is SMTP?
-simple mail transfer protocol
- governs sending of emails over a network to a mail server
what is IMAP?
-internet message access protocol
-governs retrieving emails from email servers
what is layering?
the concept of breaking up communication into separate components or activities
each component handles a different part of the communication
- layering enables standards to be put in place and simply adapted as new hardware and software is developed
what is the application layer?
applications such as web browsers and email programs operate at this layer
- https, smtp, imap, ftp
what is the transport layer?
-breaks down the message into packets
-each packet is given a packet number and the total number of packets
-sets up communication between hosts
-tcp, udp
what is the network/internet layer?
-adds the sender’s and recipient’s IP addresses to the packet and packages the data to make it ready for transmission
-routes the packets across the network
what is the link layer?
-the NIC and operating system drivers are at this layer
what are standards?
an agreed way of doing things
why is layering useful?
-allows standards to be developed
-be adapted to new hardware and software over time
what is authentication?
-the process of a user confirming their identity on a computer system
what are the three factors of authentication?
-something you are: username, bank number
-something you know: password, pin
-something you have: biometrics, card
what is encryption?
the process of disguising a message so it cannot be understood by anyone but the intended recipient
ENCRYPTION DOES NOT PREVEN INTERCEPTION IT PREVENTS UNDERSTANDING
how does the Caesar cipher work?
-it gives a number value to a key
-each plaintext letter is replaced by a new letter, the one found at the original letter’s position in the alphabet plus the value of the key
what is a firewall?
-a software that blocks unexpected connections coming into or out of a network
how do firewalls work?
-they use ports which only allow specific data into and out of networks
-the network manager is able to open or close the pots depending on the type of traffic they want for the network
what is MAC address filtering?
blocking incoming traffic based on their MAC address
what is a whitelist?
only the device addresses on the list are allowed to access the network
