Session Objectives#18
COULD explain the need for IP addressing of resources on the internet and how this
can be facilitated by the role of DNS services
SHOULD Describe the differences between lossy and lossless compression and explain
the importance of compressing files that are transmitted via the internet
MUST describe common file standards associated with the internet such as
JPG,GIF,PDF,MP3,MPEG.
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Key Words
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IP & MAC Addresses
What is this??
72.163.4.161 IP Address of Cisco Headquarters, California, USA
To the computer this address is made 32 bits or 4 bytes
which it converts each into binary. Going from left to
right what is the binary equivalent?
01001000, 10100011, 00000100, 10100001
Or 01001000101000110000010010100001
You can see why humans prefer to use denary!
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IP & MAC Addresses
IP Addresses are unique to an individual computers location over
the internet. The addresses are acquired by the Internet Service
Provider (ISP) or a DHCP server or Dynamic Host Control Protocol
for an internal network.
A Smartphone is the same, it is issued with an IP address from
DHCP server at the mobile carrier. It may change during the day
but will unique for the time it has been assigned.
TASK: Check to see your current IP address.
MAC Addresses – These are still unique identifiers but are hard
coded into each device. They are much bigger – 48 bits – and
uniquely identify each device in the world.
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IP & MAC Addresses
IP Addresses
MAC Addresses
32 bits
48 bits
4 sets of decimals
6 pairs of hexadecimals
Can be changed manually or
assigned automatically by a
DHCP server
Permanently ‘hard coded’ into
each device in the world.
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File Compression
TASK 1: Use the following online tool and compress some images:
http://compressnow.com/# Use Chrome!
Now answer these questions in your notes:
What is compression? What affect does it have and why use it?
Research and create a comparison table of lossy and lossless
compression algorithms.
Lossy
Lossy
Lossless
Lossless
Data is lost when compressed
Data is retrieved when decompressed
Some data lost but hardly noticeable
Restored completely to original
Greatest file reduction made
Not as much data can be reduced
Most common form for Internet use as
download speed is paramount
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File standards of the Internet
TASK:
Use the 2UP view in Fireworks and experiment optimising
different file types. Then complete the following table
explaining the circumstances which each file type would be used.
File Type
Description/Explanations
GIF
JPG
PDF
MPEG
ZIP
MP3
EXT: Extend the table to include other files associated with the
Internet.
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