Zusammenfassung der Ressource
Networks and
Communications
- Types of Network
- Wide Area Network (WAN)
- Covers a large geographical
area e.g internet
- Local Area Network (LAN)
- Covers a small area
e.g. school, home, etc.
- Cabling can be expensive, large network managing is complicated, if file server
breaks down the servers become inaccessible, viruses can spread, danger of hacking.
- Sharing devices saves money, easy file sharing, easy (instant) communication, easy backing up data on file server
- Internet
- An
international
network of
computers.
- WWW is only part of the internet.
Other parts include: email, instant
messaging and file sharing.
- Types
- Dial Up
- Cable
modem
- Leased line ; A connection that has been paid for
by a company, only they can use it and it is a
permanent connection between two distinct places.
- ISDN - Integrated Service Digital Network ; Uses digital transmission
and can transfer data and voice at the same time. Faster than dial-up.
- ADSL - Asynchronous Digital Subscriber Line ;
faster than dial-up connection, uses telephone lines.
- Emails
- Spam, phishing (scams), viruses can
easily spread through attachments,
recipient needs access to internet, no
guarantee that email will be read.
- Fast delivery, can be sent
whenever, cheap, can be sent to
one or several people at once.
- Definition
- A number of computers linked
together to allow them to share
resources. Networked computers can
share hardware, software and data.
- Network Topologies
- Bus Network
- Easy to install, cheap
- If main cable fails, the
whole system will too.
Slow. Security at risk.
- Star Network
- expensive (cable), extra
hardware (hubs/switches)
required, if hub/switch fails all
devices will have no connection.
- Reliable, high performance,
no data collisions
- Ring Network
- Quick, no
data
collisions.
- If main cable fails, the
whole network will too.