structure of the internet Flashcards
What is the internet?
A massive network of connected computers and devices, a massive collection of domain-named server routers
What is often thought of as the backbone of the internet?
There are lots of high volume fibre optic cables that run for miles under the sea that connect different countries to a network allowing massive amounts of data to be transmitted between countries
What do routing tables do?
- They store and update the locations of other network devices
- They tell computers where to go to find the correct resources.
What is the route a request for data takes?
It goes down to local isps and domain-named servers then to up to larger regional ones, then to huge network service provider DNSs, whose look up tables contain billions and billions of websites
What happens when a request is received?
Your data packets are routed across many many different routes, the same message is split into many packets and the packets can take different routes
Why do data packets take different routes?
- The packets take the faster or least congested route available
What does a router do?
- They receive packets and forward them to the correct destination by reading the recipient’s IP address
- It uses its look up table to pass the data packet along the best or fastest route
What does a gateway do?
- They receive and forward data packets on to the correct destination based on the address on it
- They deal with packets travelling between devices that use different protocols
How do individuals and organisations connect to the internet?
They connect to the internet through an internet service provider (ISP), this may be via telephone connection or a dedicated fibre-optic cable to their house.
What does a network access device contain?
Network access devices contain a WAP, a switch, a router, and often a modem. The Ethernet switch can usually be recognised as four external ports, labelled ‘LAN’, and the connector to the ISP is usually labelled ‘WAN’ or ‘internet’.
What is the difference between having the WAN connecter as an Ethernet port and having the WAN connecter as a phone socket or coaxial connector?
- If the WAN connector is an Ethernet port, a separate modem is required
- If the WAN connector is a phone socket or coaxial connector, the modem is built into the network access device.
What is a modem?
-A modem converts between analogue and digital signals so that it can be sent through a cable that uses different technology
How do gateways deal with packets travelling between devices that use different protocols?
They strip away the packets header, leaving just the packet’s contents.
Then they give the packets new sender and receiver addresses which comply to the new protocol. Then it forwards it on.
