AQA A-Level Computer Science - The
Internet, Big Data and 1.15 abstraction
Exam Study Guide
The Internet
The Internet - Answer>>A network of interconnected computer
networks.
- Mostly wired network
- Has cables that pass under oceans to connect different
continents.
Internet Service Provider (ISP) - Answer>>A company that
provides its customers with access to the internet.
Explain the process of Packet switching - Answer>>- Firstly, a
message is split into multiple packets.
- Each packet is then sent to its recipient via the best possible
route.
- They pass through a number of routers before they reach their
destination.
- The router uses their recipients address to determine where to
send the packets
- Once it has finally reached the recipient it's will be reassembled.
Packet - Answer>>A container that data is stored in to be
transmitted over networks.
- They contain both the sender and recipients addresses
- They contain information for the intended recipient
- They contain TTL (Time to Live)
- Sequence number
, Sequence Number - Answer>>- Allows packets to be
reassembled in the correct order.
Routers - Answer>>- They send packets to their recipient via
the fastest possible route.
- This might be the route that has the lowest number of hops or is
the least congested.
- Routers hold tables with information relating to the fastest
possible routes to certain devices, which they frequently update.
Gateways - Answer>>- They send data between networks with
different protocols.
- They strip away most of the packet's details leaving only the
contents and then provide them with new addresses that comply
to the new protocol.
URL (Uniform Resource Locator) - Answer>>An address
assigned to files on the internet.
https:// (Hypertext Transfer Protocol Secure) - Answer>>The
protocol being used to access a file.
www. (World Wide Web) - Answer>>- Subdomain for the WWW
- Points to the web server hosted at the following domain.
bbc.co.uk - Answer>>- Domain
/news - Answer>>Directory of the file being requested
/index - Answer>>Name of the file being requested
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