Layer No.
Name
Description
Protocols*
Responsible party*
7 (highest)
Application
Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services (authentication and privacy/security). Telnet and FTP are applications that exist entirely in the application level.
DNS, FTP, HTTP, SMTP,
Software applications (small utilities to major application suites)
6
Presentation
The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer.
HTML
GIF
TIFF
JPEG
ASCII
Client...