Syngress - Eleventh Hour Network+ Exam N10-004 Study Guide (11 ...

78 CHAPTER 5 The OSI Model and Networking Protocols
networking software. Everything that occurs at this level is application-specific.
File sharing, remote printer access, network monitoring and management,
Remote Procedure Calls (RPCs), and all forms of electronic messaging occur
at this level.
Samples of application layer protocols are File Transfer Protocol (FTP), Telnet,
Simple Mail Transfer Protocol (SMTP), Post Office Protocol 3 (POP3), Internet
Message Access Protocol 4 (IMAP4), Hypertext Transfer Protocol (HTTP),
Network News Transfer Protocol (NNTP), and Simple Network Management
Protocol (SNMP). Be sure to distinguish between the protocols mentioned and
applications that may bear the same names. For instance, there are many different
FTP programs made by different software vendors, but all of them use the FTP
protocol to transfer files.
EXAM WARNING
Knowing the OSI model is imperative. You will need to know which devices and protocols
function at each layer, so you need to know the layers to start with. Continue to draw the
model shown in Figure 5.1 so that when you get to the exam, you can write it on scrap
paper to help you with the exam.
The Microsoft Model
With the release of Windows NT 3.1, TCP/IP was built into the operating system,
providing a seamless integration of networking functionality in the OS. Since
that time, it has become standard to provide TCP/IP with the operating system
since so many computers today connect to a network in one form or another.
DID YOU KNOW
The Microsoft model provides a standard platform for application developers. This modular
design enables the developer to rely upon the underlying services of the OS through the
use of standard interfaces. These interfaces provide specific functionality developers
that can be used as building blocks to develop an application. This makes development
time shorter and provides common interfaces for users, making learning and using new
applications easier.
UNDERSTANDING THE FUNCTION OF BOUNDARY LAYERS
The Microsoft model describes software and hardware components and the
connections between them that facilitate computer networking. This modular
approach both allows and encourages hardware and software vendors to develop
products that work together through the Microsoft operating system. Boundary
layers are interfaces that reside at the boundaries of functionality. They interact
with the layer below and the layer above, providing an interface from one layer
to the next.