Networks Flashcards
Define a protocol
A set of rules for communication between devices
Define Layering
The principle of dividing a complex problem into separate, independent sub-problems
ADV of layering
- Allows the creation and maintenance of parts of a system without having to take the whole system into account
- Protocols on each layer communicate only with the layers above and below. This means that a protocol on any layer can be changed for another protocol providing it receives and passes data in the same manner
What are the layers in the TCP/IP stack
application, transport, internet and link
Purpose of the application layer and examples of protocols
Concerned with production and reception of data. Packages data and passes it to the transport layer. HTTP, IMAP, DNS
Purpose of the transport layer and examples of protocols
Concerned with making and breaking connections via routers. TCP, UDP
Purpose of the internet layer and examples of protocols
Concerned with providing links across different network types. Essential feature of the internet that allows interoperability between all connected systems. IPV4, IPV6
Purpose of the link layer and examples of protocols
Passes data to the physical network. It can work with any media such as copper wire, optical fibre and wireless. Wi-Fi, Ethernet
How is IPv4 structured
Four 8-bit numbers, represented in denary
How is IPv6 structured
Eight 16-bit numbers, represented in hex
What is the Uniform Resource Locator (URL)
The main part of a website address, e.g. hodder.co.uk
What is the Domain Name Server (DNS)
A method that computers use to find the correct IP addresses given the URL
Describe the steps when looking up the IP address of a URL
- Computer checks its local cache to see if the IP address has previously been found
- If there isn’t a copy, then it checks one of the root servers
- If it doesn’t have a copy, it points to a server matching the top-level domain (TLD) like .com or .uk
- These may point to second level domains
- Finally comes the authoritative name server that holds the IP address of the server being sought. This is sent back to the browser so it can visit the site
Define LANs
Local Area Networks are networks over a defined and limited location
Define WANs
Wide Area Networks cover a large geographical area
Define circuit switching
A pathway for the data is set up in advance of communication and then data is sent across it. The pathway is closed after transmission
Define packet swithcing
Packages of data are sent across a network. They may take different routes and are reassembled by the receiver
Define data packets
Data is broken down into chunks called packets when sent across a network
How is a data packet split
Header, Payload and Trailer
What does the header contain
Source address, destination address, packet sequence number and protocol
What does the payload contain
Data
What does the trailer contain
Checksum and End of packet marker
Define hacking
The process of gaining unauthorised access to a computer system
What is a firewall
Software or hardware that can inspect and block incoming and outgoing network data
What is a proxy
A server that sits between a network and the internet, through which internet data requests are made
What is a NIC
Network Interface Card allows a computer to connect to a network
What is a router
Connect networks to the internet
What is a hub
Connects devices together to form a network and broadcasts all data to all possible destinations
What is a switch
Connects devices together to form a network and directs data only through the port to which the destination device is connected
What is a wireless access point
A device that is connected to a wired network and then provides a wireless signal
