Group of applications requiring
network communications
Transport
Establishes the connection between
applications on differnt hosts
Network
Responsible for creating packets
that move across a network
Data link
Responsible for creating frames that move across
a network
Physical
The transceiver that drives
the signals on the network
Types of Topology
Bus
Cost effective, easy to add more
computers, quick set up
Data collisions are more liekly
Ring
Data is quickly
transferred, prevents
network collisions
If there is a problem with the main cable
the network will shut down
Star
Good performance,
better security
Expensive, extra hardware neede like
a hub or switch
Mesh
Manages high amount of traffic, a failure of
one device does not cause break in
network
Expensive, bulk wiring,
building and maintaining is
difficult
DNS server
This is when the DNS checks the local cache to see if the IP
address of what a person has typed in matches with anything
inside it. If not then it will go down the hierarchy to each DNS
server to check if there is a match.When it is found it will go
back up the hierarchy and stored in the local cache. After that
the web-page is loaded up