Networking Flashcards
Define Topology
Different arrangements of computer connections and devices
Describe a bus topology
A central cable is used to connect all the devices with terminators at the end of the cable so the signal doesn’t bounce back
What is a backbone?
The central cable in a bus topology
How does a bus topology send signals?
A signal is sent via the main cable which reaches all the the connected devices
The signal contains a destination address to identify the recipient and a source address to identify the sender
MAC address are hardcoded in the Network Interface Controller of each device
Devices must detect if they are transmitting at the same time so they can stop to avoid collision
What is the disadvantages of bus topology?
A bus setup doesn’t allow 2 computers to transmit at the same time as it causes collisions
When network is in heavy use, the overall performance decreases as collisions increase
If the main cable breaks it brings the whole network to a stop
Devices can eavesdrop on each other
Define Mac address
Media Access Control address- An address given to a network interface controller used to uniquely identify devices on a local network
Define NIC
Network Interface Controller- A component that allows a device to connect to a network
What’s Ethernet?
A bus topology with a coaxial cable as the backbone
All the computers are connected by a special interface cable which plugged into a NIC connecting the computer and the cable
The ethernet protocol
Includes the CSMA/CD rules and the need to send destination and recipient MAC addresses
Specifies the structure of the data sent via hardware
What’s an ethernet frame?
A blue print for the structure of data, it has 5 different fields for the pieces of information needed for transmission
What are the 5 fields of an ethernet frame?
Data transmitted Destination address Source address Type field FCS (Frame check sequence)
What is the FCS?
Frame Check Sequence- Used to detect whether errors have occurred during transmission
What is a UTP (ethernet) cable?
Unshielded Twisted Pair cable, a type of cable where two conductors are twisted together to reduce interference
Explain a Star topology if the central device is a hub
A UTP cable connects each computer to a central device (e.g. a hub) which sends signals to all the computers
Each cable acts like a bus network as the hub has no understanding of what the signals mean
What’s a Switch?
A network computer that is used to connect devices on a LAN, it learns which device is connected to each port so it can direct traffic
Explain a Star topology if the central device is a switch
A UTP cable connects each computer to a central device (e.g. a switch) which sends signals to all the computers
The switch learns the address of each device connected to its ports by looking at source MAC addresses.
It builds a table mapping each port-device connection so it can direct incoming data to a specific device
If an unknow destination address is sent it defaults to hub behaviour
What’s needed for a client- server network
A central powerful computer (server)
Client computers
Define server
A computer on a network that provides resources to be used by authorised clients
Access level granted by the server is controlled by the handler
Explain Web servers
The most common type of server
Store and provide webpages
What’s a client?
A computer or computer controlled device that provides user access to a network
They run software to make requests to servers then interpret/display the response
They send requests to the server which processes it and returns it
What is client-sever networking used for?
Web services, game hosting and private networks
How does peer-peer networking work?
No central server
All computers have equal roles & access rights
They share portions of their resources
Network security & resource management is not controlled centrally so backs have to occur locally
What is peer-peer networking used for?
LANs, file sharing networks
What is a wireless security protocol?
A set of rules specific to wireless communication
WEP
how it works
pros
cons
Wired Equivalent Privacy
Designed to have the same security as a wired network
Uses symmetric encryption (same key to en and de -crypt)
Sufficient for first line of defence
WEP keys are too short & used for too long
Keys are easy to decipher
WPA
how it works
pros
cons
WiFi Protected Access
Temporary improvement to WEP
Introduced key management
Generates a new encryption key for each packet
Keys are larger
WPA2
how it works
pros
cons
WiFi Protected Access 2
An improvement on WPA that provides a stronger encryption algorithm
What is an SSID
Service Set Identifier
A string of alphanumeric characters specified during the setup of wireless devices
How do SSIDs work?
Broadcast for all to see
Passwords are often used to allow devices to connect
What are the 2 most common frequencies for WiFi?
2.4GHz
5GHz
