Networks Flashcards
What does LAN stand for?
Local Area Network
What area does a LAN cover?
A small geographical area located on a single site
Who owns the hardware for a LAN?
The organisation that uses it
Are LANs wired, wireless, or both?
Both
Where are LANs used?
1) Businesses
2) Schools
3) Universities
What does WAN stand for?
Wide Area Network
What does a WAN connect?
LANs that are in different geographical locations
How can WANs be connected?
1) Telephone lines (copper or fibre optic)
2) Satellite links
3) Radio links
What is the biggest WAN?
The Internet
What does PAN stand for?
Personal Area Network
What area does a PAN cover?
Devices over a very short range
What devices are often connected in a PAN?
1) Smartphones
2) Smartwatches
3) Headphones
What wireless technology do PANs use to connect devices?
Bluetooth
What are the advantages of networking computers?
1) Sharing files is easier
- Network users can access the same files, work on
them at the same time and copy files between
machines
2) Can share the same hardware (like printers) between multiple devices
3) Can install and update software centrally on all computers at once
4) Can communicate easily and cheaply across a network
5) User accounts can be stored centrally, so users can log in from any device on the network
What are the disadvantages of networking computers?
1) Can be expensive to set up as a lot of extra hardware is often required
2) Networks can be vulnerable to hacking, and malware can easily spread between networked computers
3) Some networks are dependent on one or more servers
-If those servers go down it can be very disruptive
for people trying to use the network
4) Large networks are difficult to manage and may require employing a specialist to maintain them
What is a NIC used for?
Allows a device to connect to networks
What is a switch used for?
To connect devices on a LAN
What is a router used for?
1) To transmit data between different networks
2) To connect to the Internet
What is bandwidth?
The amount of data that can be sent across a network in a given time
How are devices connected in a star topology?
All the devices are connected to a central switch or server that controls the network
What are the advantages of a star topology?
1) If a device fails or a cable is disconnected, the rest of the network is unaffected
2) Easy to add more devices to the network, since each device is connected to the switch using a separate cable
3) Tend to have better performance than other setups - data goes straight to the central device so all devices can transmit data at the same time
4) Very few data collisions on a star network compared with other network topologies
What are the disadvantages of a star topology?
1) In wired networks, every device needs a cable to connect to the central switch or server. This can be expensive .
2) Switch is an expensive piece of hardware
3) Problem with switch or server affects the whole network
4) Maximum number of possible connections on the network is determined by the switch - new switch may be required for more connections
How are devices connected in a bus topology?
Bus topologies use a single ‘backbone’ cable, called a bus, to connect all the devices
Why are two terminators placed at the end of the bus?
1) Stop data reflecting back along the bus
- Without the terminators, reflected signals would cause interference and potentially make network unusable
What are the advantages of a bus topology?
1) Network is unaffected if a device fails
2) Not dependent on a central switch working to keep the whole network running
3) Relatively cheap to set up compared to star networks. The total length of wiring needed is much less, and the hardware you need is cheaper than switches, both to buy and to maintain
What are the disadvantages of a bus topology?
1) Data collisions are common. When there is a data collision the data must be resent, which slows the network down
2) More devices you add to the network , the more likely data collisions are. This makes bus topologies unsuitable for large networks
3) To try and avoid data collisions, devices must wait for the bus to be available before they can send any data - this can also slow the network down
4) if the bus cable gets broken, it splits the network into separate parts. Since the separated networks don’t have terminators at both ends of the bus, there will be a lot of reflected signals which can shut down the entire network
What is the definition of a protocol?
A protocol is a set of rules for how devices communicate and how data is transmitted across a network
How is data send between networks?
Equal-sized packets
What is a layer?
A group of protocols which have similar functions
What are the 4 layers of the TCP/IP protocol model?
Layer 4 - Application Layer
Layer 3 - Transport Layer
Layer 2 - Network Layer
Layer 1 - Link Layer
What is the role of the application layer?
Providing networking services to applications
What are some protocol examples for the application layer?
1) HTTP
2) HTTPS
3) IMAP
4) FTP
5) SMTP
What is the role of the transport layer?
Setting up communications between two devices, splitting data into packets and checking packets are correctly sent and delivered
What are some protocol examples for the transport layer?
1) TCP
2) UDP
What is the role of the internet layer?
Adding IP addresses to data packets, directing them between devices and handling traffic. Used by routers
What are some protocol examples for the internet layer?
1) IP
What is the role of the link layer?
Passing data over the physical network. Responsible for how data is sent as electrical signals over cables, wireless and other hardware
What are some protocol examples for the link layer?
1) Wi-Fi
2) Ethernet
What are the advantages of using layers?
1) it breaks network communication into manageable pieces. This helps developers concentrate on only one area of the network without having to worry about the others
2) as layers are self-contained, they can be changed without the other layers being affected
3) having set rules for each layer forces companies to make compatible, universal hardware and software, so different brands will work with each other and always work in basically the same way
What does HTTP stand for?
Hyper Text Transfer Protocol
What does HTTPS stand for?
HTTP Secure
What does FTP stand for?
File Transfer Protocol
What does IMAP stand for?
Internet Message Access Protocol
What does SMTP stand for?
Simple Mail Transfer Protocol
What is HTTP used for?
Used by web browsers to access websites and communicate with web servers
What is HTTPS used for?
A more secure version of HTTP. Encrypts all information sent and received
What is FTP used for?
To access, edit and move files between devices on a network
What is IMAP used for?
To retrieve emails from a server
What is SMTP used for?
To send emails. Also used to transfer emails between servers
What does TCP stand for?
Transmission Control Protocol
What does UDP stand for?
User Datagram Protocol
What is TCP used for?
1) establishing a connection between the sending and receiving devices
2) communicating with the receiving device to make sure that all packets have been transferred correctly
What is UDP used for?
1) breaking down the data into packets without numbering them
2) sending packets once and not checking with the receiving device that everything everything has been received
What does IP stand for?
Internet Protocol
What is IP used for?
1) establishing connections between routers
2) handling network traffic
3) directing data packets to their destination across the internet or other IP networks - packet switching
What is Wi-Fi?
A family of protocols commonly used in WLANs
What layer does Wi-Fi operate on?
Link Layer
What two radio frequency bands does Wi-Fi use?
1) 2.4GHz
2) 5GHz
When is UDP suitable?
For applications that need fast, efficient transmission
Give an example of when you would use UDP.
Live video streaming
When is TCP suitable?
When you need a reliable connection
Give an example of when you would use TCP.
Downloading files
How does packet switching work?
1) each packet is sent between a series of routers
2) each router reads the packet’s header and uses the IP address to decide which router to send the packet to next
What does WPA stand for?
Wi-Fi Protected Access
What does WPA do?
Encrypts data on Wi-Fi networks
List some ways of protecting networks against threats.
1) encryption
2) anti-malware software
3) automatic software updates
4) user access levels
5) MAC address filtering
What is encryption?
When data is translated into a code which only someone with the correct key can access, meaning unauthorised users cannot read it
What is encrypted text called?
Cipher text
What do automatic software updates do?
Patch (fix) any identified security holes in a piece of software
What does MAC address filtering do?
Makes sure the only people on a network are trusted users. It checks the unique identification (MAC address) of each device that tries to connect to the network and only lets allowed devices join the network
What does user authentication do?
Prevents unauthorised people from accessing data from the network
What precautions should you take with your passwords?
1) long
2) a combination of letters, numbers and symbols
3) changed regularly
What are biometric measures?
1) Scanners to identify people by a unique part of their body
List some example of biometric measures.
1) fingerprint
2) retina
3) voice
Why is email confirmation used?
1) to confirm that the email address belongs to the person registering
2) to stop people from using fake email addresses to sign up for things
What is a CAPTCHA test designed to do?
Prevent programs from automatically doing certain things
