Comp theory - Networks

how to calculate network speed (bits per sec)

data transferred (in bits) / time (in sec)

latency

time between information sent to received

LAN vs WAN

LAN: uses cabling owned by company; spread over small geographical area (single location/site)

WAN: uses third party cabling to transfer data between geographically remote sites

How is data sent across internet

The data is broken down into small packets. Each packet is numbered, given the sender’s and recipient’s IP address and sent separately.

Packets can take different routes through the Internet, based on the most efficient route. Packets are reassembled at the destination and checked for errors lost or corrupted packets are resent.

Benefits of TCP/IP layers

each layer self-contained so can be changed without affecting other layers

developers can concentrate on one network area without worrying how others work

Pros and Cons of Mesh Topology

Pros: no central point of failure; data can be transmitted from different devices simultaneously

Cons: can be expensive to install; due to redundant connections network maintenance and administration is more complicated

what is a protocol

a set of rules

how are emails sent by SMTP

A’s email is sent to a local mail server/SMTP server.

the mail server forwards this to B’s mail server via the internet

it is forwarded to more servers along the way until it reaches B’s mail server

external hazard that firewall protects computer from

attack of network ports

attacks from IP addresses that are known to perform malicious attacks

how does a firewall provide security when your computer is connected to internet

Prevents unauthorised access to your computer by people accessing it from the internet
Configured to block traffic from specific IP addresses

or block access to certain ports or applications/services but allow certain ports/services access.

physical security measures for network security

A lock on the server cabinet / a lock on the server room door would make it harder for hackers to gain access to the servers.
ID could be worn by all IT technicians so that anyone else accessing the network/servers could be challenged.
Locks could be used on the perimeter doors of the school to make theft harder when the school is not open.
A security alarm could be used when the school isn’t open so that any intruder is put off by the noise / the police are phoned as soon as there is an intrusion.

define bandwidth

the maximum amount of data that can be transferred over a network connection in a specific time