CCNA Cisco Certified Network Associate Study Guide - FTP Server

8 Chapter 1 � Internetworking
E-mail gateways Are versatile and can use Simple Mail Transfer Protocol
(SMTP) or the X.400 standard to deliver messages between different
e-mail applications.
Electronic Data Interchange (EDI) Is a composite of specialized standards
and processes that facilitates the flow of tasks such as accounting,
shipping/receiving, and order and inventory tracking between businesses.
Special interest bulletin boards Include the many Internet chat rooms
where people can connect and communicate with each other either by
posting messages or by typing a live conversation. They can also share
public domain software.
Internet navigation utilities Include applications like Gopher and
WAIS, as well as search engines like Yahoo!, Excite, and Alta Vista, which
help users locate the resources and information they need on the Internet.
Financial transaction services Target the financial community. They
gather and sell information pertaining to investments, market trading,
commodities, currency exchange rates, and credit data to their subscribers.
The Presentation Layer
The Presentation layer gets its name from its purpose: It presents data to the
Application layer. It’s essentially a translator and provides coding and conversion
functions. A successful data transfer technique is to adapt the data
into a standard format before transmission. Computers are configured to
receive this generically formatted data and then convert the data back into its
native format for actual reading (for example, EBCDIC to ASCII). By providing
translation services, the Presentation layer ensures that data transferred
from the Application layer of one system can be read by the
Application layer of another host.
The OSI has protocol standards that define how standard data should be
formatted. Tasks like data compression, decompression, encryption, and
decryption are associated with this layer. Some Presentation layer standards
are involved in multimedia operations. The following serve to direct graphic
and visual image presentation:
PICT This is picture format used by Macintosh or PowerPC programs
for transferring QuickDraw graphics.
TIFF The Tagged Image File Format is a standard graphics format for
high-resolution, bitmapped images.