CompTIA® netplus (n10-003) tutorials and Test Questions Guaranteed pass

This 7-layer model was designed for a number of reasons:

It helps one to understand how a network operates.
It allows for multi-vendor support through the standardization of network components. I.E. different
types of network hardware and software components can communicate. (This is a good thing.)
Changes in one layer will not affect the other layers, which aids in development.
A thorough understanding of the 7-layer model, its hardware and software components is absolutely
essential for the Network+ exam, and even more so for the CCNA exam.
Layer 7 Application layer
Layer 6 Presentation layer
Layer 5 Session layer
Layer 4 Transport layer
Layer 3 Network layer
Layer 2 Data Link layer
Data link sublayer Logical link control meets IEEE 802.2 standards
Data link sublayer Media access control meets IEEE 802.3 standards
Layer 1 Physical layer
Upper layers of the OSI model
Application layer - At the top of the OSI model the Application layer is responsible for determining whether or not there are sufficient resources for communication. Some of the services that may be found here would be E-mail, file and print sharing, just to name a few.
Presentation layer - The Presentation layer is responsible for formatting, encrypting, and compressing user data. It ensures that when data is sent, it may be presented at the receiving end, in a recognizable format.
Formats found at the Presentation layer are:
Graphics - JPEG, TIFF, GIF
Text and Data, ASCII, EBCDIC
>Sound and Video, MPEG, MIDI, QuickTime
Session layer - The primary purpose of this layer is to establish, maintain, and terminate sessions (dialogues). Communication is coordinated here by offering any one of three different modes of data transmission.
They are simplex, half-duplex, and full duplex.
A few of the protocols that are found at the Session layer are:
Network File System (NFS), SQL (Structured Query Language)
RPC (Remote Procedure Call)
ASP (AppleTalk Session Protocol).
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