The application layer is the top layer of the OSI model and controls how applications communicate over a network. It provides services for applications including mail, file transfer, domain name translation and network security. Protocols at this layer include HTTP, FTP, SMTP, DNS and others that allow applications to access remote files and exchange messages over the internet in a standardized way. The application layer hides the complexities of the underlying network from applications and ensures reliable and secure communication between devices.

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Dr. C.V. Suresh Babu
Application Layer

2. It's an abstraction layer
service that masks the rest of
the application from the
transmission process.
2
The application layer is a component
within an application that controls the
communication method to other
devices

3. 3

4. 4
• Application layer is used exchange messages.
• It provides access for global information about
various services.
• It helps us to access files and manages it.
This layer has many responsibilities, including
• error handling and recovery,
• data flow over a network and full network flow.
It is also used to develop network-based
applications.

5. 5

6. Functions of Application Layer
• Mail Services: This layer provides the basis for
E-mail forwarding and storage.
• Network Virtual Terminal: It allows a user to
log on to a remote host.
• Directory Services: This layer provides access
for global information about various services.
• File Transfer, Access and Management
(FTAM): Users can access files in a remote
computer and manage it.
6

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Protocol is a set
of rules and
regulations that
determine how
data is
transmitted in
telecommunica
tions and
computer
networking.
Application Layer

8. • Domain Name Space (DNS)
• SMTP
• FTP
• HTTP
• WWW
• Security
• Cryptography 8

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The Domain Name System (DNS) is the phonebook
of the Internet. Humans access information online
through domain names, like google.com or
facebook.com. Web browsers interact through
Internet Protocol (IP) addresses.
DNS translates domain names to IP addresses so
browsers can load Internet resources.

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SMTP is a set of communication guidelines that allow
software to transmit an electronic mail over the internet is
called Simple Mail Transfer Protocol. It is a program used for
sending messages to other computer users based on e-mail
addresses.

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FTP (File
Transfer
Protocol) is the
commonly used
protocol for
exchanging files
over the
Internet
FTP works in the same way as HTTP and SMTP.

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HTTP (Hyper Text Transfer Protocol) is the underlying
protocol used by the World Wide Web and this protocol
defines how messages are formatted and transmitted, and
what actions Web servers and browsers should take in
response to various commands.

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The World Wide Web (WWW) is a
network of online content that is
formatted in HTML and accessed via
HTTP. The term refers to all the
interlinked HTML pages that can be
accessed over the Internet

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Network security is a broad term that covers a multitude of
technologies, devices and processes.
In its simplest term, it is a set of rules and
configurations designed to protect the integrity,
confidentiality and accessibility of computer networks
and data using both software and hardware
technologies

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Cryptography not only protects data from theft or alteration,
but can also be used for user authentication.
It refers to secure information and communication
techniques derived from mathematical concepts and a set
of rule-based calculations called algorithms to transform
messages in ways that are hard to decipher.