Fundamental Of computer network part 01

Part 01 

Details Of OSI 7 Layer
There are 7 layer of OSI model (Open system Interconnection). Its counted Top to down.

7 . Application Layer
6 . Presentation Layer
5 . session Layer
4 . Transport Layer
3 . Network Layer
2 . Data Link Layer
1 . Physical Layer

For us to remember. We'll use a method

[All People Seem To Need Data Process]
 Just remember this sentence.


7. Application Layer :
Example: MSN messenger, Yahoo Messenger, web browser (its not completely use up. Only HTTP use for this layer ) etc

6 . Presentation Layer :
Its called, what is the format of data ?

when we browse internet. we are saw many kind of page. Those page has a file which we  are download everyday.

These are included in the layer.
There are four thing in presentation layer

a. Encryption
b. Decryption
c. Compression
d. Decompression


a. Encryption/Decryption:
Example: If Our file name. World-Tech-Zone.exe
and convert the world-tech-zone.exe as a name hdfgjfdh.exe



World-Tech-Zone.exe(convert to)
 hdfgjfdh. its called encryption

hdfgjfdh(convert or decoded to)
 World-Tech-Zone.exe. its called decryption.


b.  Compression/Decompression:


Example: If our file size 'fff.exe' 12MB

fff.exe(12MB)
when we use compression
fff.exe(9MB)
its will show 9MB. Just for example



when fff.exe (9MB) decompression. it will show original size.
fff.exe (12MB)

Coming Up Next ...............