SLR 11 - Networks Flashcards
What is a network?
A group of connected devices
What are the advantages of networks?
Users can share files
Users can share peripherals and connections to other networks
Users can share and access files from any computer in the network
Servers can control security, software and backups
What are the disadvantages of networks?
Increased security risks
Malware spreads easily
If a server fails, networks may fail
Computers may run slowly if a lot a data is being processed in the network
What are standards?
A set of specifications that allow manufacturers to make compatible products
An example is the use of protocols
What protocols are used to communicate over a network?
TCP - Transmission Control Protocol
IP - Internet Protocol
UDP - User datagram Protocol
What protocols are involved in webpage requests?
HTTP - Hypertext Transfer Protocol
HTTPS - Hyptertext Transfer Protocol Secure
What protocol is involved in file transfers?
FTP - File Transfer Protocol
What protocols are involved in Email requests?
POP - Post Office Protocol
IMAP - Internet Message Access Protocol
SMTP - Simple Mail Transfer Protocol
What are routers?
Connect to Internet Service Providers
ISPs connect to the DNS and other routers
What do modern routers connect too?
Devices on the LAN
Other routers on a WAN
Servers
What is layering?
The decomposition of networking
Hardware / Software in each layer has a set responsibility providing services to later layers
What are the advantages of layering?
Decomposition
Devices can be manufactured to operate at particular layers
What is the most important protocol stack?
TCP / IP
What are the layers of TCP / IP?
Application
Transport
Internet
Link
What happens in the Application layer?
Network applications request data or webpages
What protocols are in the Application layer?
FTP / HTTP / HTTPS / SMTP / IMAP
What happens in the Transport layer?
Between 2 hosts settings are agreed and applied
What protocols in the Transport layer?
TCP / UDP
What happens in the internet layer?
The router address and packages data for transmission, it routes packets across a network
What protocols are in the internet layer?
IP
What happens in the Link layer?
Network hardware sets standards and facilitates binary transmission
What are mediums can be used for link transmission?
Copper Wire, Fibre, WiFi
What is TCP responsible for?
Establishing and maintaining end - end connections
What does TCP add to split packets?
Its number in the sequence
The total number of packets
The port number
What does IP add to packets?
The Source IP and destination IP
What is a socket?
The IP address + the Port Number
What does the port number contain?
The device the packet is being sent too (IP address)
The application that requested the packet (Port)
What does the link layer add to a packet?
The source and destination MAC address
These are changed every hop in a WAN
Why are both MAC and IP addresses needed?
In a LAN only the link layer is executed which creates a frame using the MAC address
In a WAN the IP addresses create a packet
How does the DNS work?
Users request a URL
This is sent to the DNS
The DNS maps the URL to an IP and returns it to a browser
A GET request is sent to the web browser
The page is then returned to the client
What is Circuit Switching?
The creation of a temporary, dedicated link between the source and destination
It guarantees transmission quality
It can waste a lot of bandwidth as only 1 user can use the route
What is the main problem with circuit switching?
It has a massive security problem due to the fact that if the wire is tapped all packets can be gained
What is Packet Switching?
It breaks down data into smaller blocks each sent independantly
It maximises bandwidth but lacks quality
It is more affordable and efficient than circuit switching
What are the problems with Packet Switching?
Packets may arrive out of order
Packets may be lost in transmission and need to be requested again
What does the server do in a client-server model?
It manages access and security
It manages internet access
Manages peripheral devices
It provides email services
It runs regular backups of data
What does the client do in a client-server model?
It makes requests to the server for data
What are the advantages of a client-server model?
It’s easier to manage security
It’s easier to backup data
It’s easier to update devices
What are the disadvantages of a client-server model?
It’s expensive to setup and maintain
It requires specialists for maintenance
The server serves as a single point of failure
Users lose access to a network on sever fail
What are client-server networks best suited for?
Organisations with large numbers of devices where many devices need access to the same set of data
What are the features of a peer-peer model?
A peer is equal to all other peers
Peers are responsible for their own security and data
Peers have their own devices
Devices must be active for communication to occur
What are the advantages of a peer-peer model?
Easy to maintain
Cheap
No dependancy on 1 connection
What are the disadvantages of a peer-peer model?
It is less secure
Users are responsible for themselves
What are Peer-Peer models best suited for?
Smaller organisations with few devices and users accessing data
