12 Networking Flashcards
What are the benefits of using LANs
Allow people to collaborate and share data easier
Centralized backup
Centralized security
Hot desking
Sharing peripherals
Name 3 network topology’s
Star
Bus
Mesh
What is star topology?
All nodes are connected to a central server/router
Name 6 advantages of star topology
Nodes aren’t reliant upon each other
Less cables than mesh so cheap
Centralized backup
More secure than bus
Data transfer is direct
Add extra devices easily
Name 2 disadvantages of star topology
If the server fails all nodes fail
If the server is far it is inconvenient to add extra devices
Name 4 advantages of bus topology
Very little cabling so cheap
Direct transfer
Nodes aren’t reliant on each other
Easy to connect devices to central wire
How does bus topology work?
All nodes are connected to a central wire (bus) which is connected to the server
What are the disadvantages of bus topology?
Data collisions are likely
All computers ‘see’ data when it is transferred
If central cable fails everything fails
More devices dramatically slow down the network
Hard to troubleshoot
What is physical topology?
The actual cabling and layout of a network
What is logical topology?
The way data is transmitted around a network
What is a mesh (peer to peer) network?
Each computer is directly connected to all others.
No central server.
List 6 disadvantages of peer to peer networks
Hard to maintain and error trap
Hard to add another device
A lot of cables so expensive
No backup
Hard to monitor
Each pc is responsible for its own security
What is WiFi?
WiFi is a standard way of wirelessly connecting devices in a network
What are the three advantages of a wireless network?
Cheaper as there’s no cables
Easy to connect new devices
Users can move around with devices
What are the three disadvantages of wireless networks?
Slower connection due to interference
Easy to intercept data
Signals can be obstructed by walls
What’s an SSID?
A sequence of characters that uniquely identifies a WiFi network.
They can be hidden so unwanted party’s can’t discover them.
What is a MAC address
A MAC address is permanent and stored in the devices NIC. It is used to uniquely identify a device.
What form are MAC addresses in?
6 sets of 2 hex digits e.g. 0B.9F.64.CD.E2.11
What is a channel?
Channels are sections of frequencies that are 22mHz wide.
Different networks use different channels to avoid interference.
What is frequency?
Data is transmitted in waves. The speed of the wave is the frequency.
How do you speed up WiFi?
Change the channel incase someone else is using it and causing interference.
What is a collision?
When two devices try to transmit data on the same channel at the same time.
How do wireless networks deal with collisions?
The CSMA/CA protocol checks if the receiving device is idle.
The RTS/CTS protocol check if devices not visible to the sender but are visible to the receiving node are transmitting.
This avoids the hidden node problem.
How does CSMA/CA and RTS/CTS work?
Assembles a frame.
Checks if channel is idle (if yes continue if no wait and check again).
Sends RTS (request to send).
If CTS (clear to send) is received back then transmit data.
Else restart the process.
How should you ensure a wireless network is secure?
- Hide the SSID
- Ensure all devices are WiFi protected WPA/WPA2
- Implement a MAC address whitelist/blacklist
