1.3.3 Networks Flashcards
What is a LAN?
A network spread over a small geographical area.
What is a WAN?
A network spread over a large geographical area, multiple LANs connected together.
What is physical topology?
The physical layout of wires and components which form the network
What is logical topology?
The layout which shows how data flows
What is the bus topology.
All terminals are connected to a backbone cable.
What are the advantages of bus topology?
● Relatively inexpensive to set up
● Doesn’t require any additional
hardware
What are the disadvantages of bus topology?
● If backbone cable fails, the entire
network gets disconnected
● As traffic increases, performance
decreases
● All computers can see the data
transmission
What is star topology?
Devices connected to a central node, often a switch . MAC addresses used to identify devices. Switch connected to server.
What are the advantages of star topology?
● Performance is consistent even with
heavy network traffic
● If one cable fails, only that single
terminal is affected
● Transmits data faster, giving better
performance than bus topology
● Easy to add new stations.
● No data collisions
What are the disadvantages of star topology?
● Expensive due to switch and cabling
● If the central switch fails, the rest of
the network fails
What is a mesh topology?
Every node connected to every other node.
What are the advantages of mesh topology?
● If using a wireless network, there is
no cabling cost
● As the number of nodes increases,
the reliability and speed of network
becomes better
● Nodes are automatically
incorporated
● Nodes don’t go through a central
switch, improving speed
What are the disadvantages of mesh topology?
● If using a wireless network, devices
with wireless capability (which
increases cost ) must be purchased
● If using a wired network, a large
quantity of cable is required
compared to other network
topologies like bus and star. This is
expensive.
● Maintaining the network is difficult
What are protocols?
A set of rules which define how two computers communicate with each other. They are standard so all devices have a method of communicating despite manufacturer.
What are the common protocols?
- HTTP
- HTTPS
- TCP/IP
- POP3
- IMAP
- FTP
What is the internet structure?
A network of networks. Continents are linked to each other using large international backbone cables.
What are the layers of TCP/IP stack.
- Application
- Transport
- Internet
- Link
What is the client/server logical structure?
- Clients request access to data from server
- Server provide data/service
What are the advantages of client/server?
- Easier to secure data
- Easier to backup data
- Easier to manage users
- Only one point of failure
What are the disadvantages of client/server?
- Expensive
- Central point of failure
What is peer to peer logical structure?
- No device has a higher status than other devices
- Devices request data/services from each other
What are the advantages of peer to peer?
- Doesnt rely on server
- Doesnt rely on single internet connection
- Less hardware investement
What are the disadvantages of peer to peer?
- Insecure
- Lots of connections
What is circuit switching?
A method of communication where a direct link is created between two devices. Link is maintained for duration of communication.
What are the advantages of circuit switching?
- Data arrives in a logical order which
results in a quicker reconstruction of the
data - Enables two users to hold a call without
delay in speech.
What are the disadvantages of circuit switching?
- Bandwidth is wasted during periods of time in which no data is being sent.
- Devices must transfer and receive data at the same rate .
- Using switches means electrical interference may be produced which can corrupt or destroy data.
- Ties up sections of the network which cannot be used by others data until transmission has been completed
What is packet switching?
A method of communication in which data is communicated using packets across a network. Packets are sent across the
most efficient route, which can vary for each packet.
What are the advantages of packet switching?
- Multiple methods to ensure data arrives intact eg. check sums and cyclic
redundancy checks - Multiple routes can be used between devices, so if one path breaks, another can be used.
- Packets can be transferred over very large networks to allow communication globally.
What are the disadvantages of packet switching
- Time is spent deconstructing and reconstructing the data packets
- Must wait for all packets to arrive before data can be received.
What is a wireless access point?
A device that sends and recieves data using radio signals.
What is frequency allocation?
- Data is broadcast at a chosen frequency
- Frequencies are split into bands, 2.4GHZ or 5GHZ
- Bands are further split into overlapping channels
What are the risks of wifi?
- Devices can be accessed without physical connection
- Bandwidth can be stolen
- Data can be intercepted
What are layers?
A step in the protocol.
What happens during the sending process of application layer?
Select an appropiate protocol
What happens during the receiving process of application layer?
Select appropiate protocol to interpret data
What happens during the sending process of transport layer?
- Split data into packets
- Add packet numbers and a port
What happens during the receiving process of transport layer?
- Removes headers
- Reassemble packets
- Requesting any missing packets
What happens during the sending process of internet layer?
- Add sender and recipient IP address
- IP is a socket
What happens during the recieving process of internet layer?
Remove headers
What happens during the sending process of link layer?
- Add the sender and recipient MAC address for next step
What happens during the recieving process of link layer?
Removes headers
What is a DNS
- A database matching IP adresses to domain names.
