Application Layer (Layer 7) tutorials

  • Layer 7 provides an interface between a hostís communication software and any necessary external applications (such as email, file transfers, and terminal emulation).

  • This layer can also evaluate what resources are necessary to communicate between two devices and determine their availability.

  • It provides following functionality:

    • Synchronization of client/server applications.

    • Error control and data integrity between applications.

    • System-independent processes to a host.

  • Following Application Protocols that are supported by Application Layer


Application Protocol

Description Function


A TCP/IP protocol that provides terminal emulation to a remote host

by creating a virtual terminal.

FTP (File Transfer Protocol)

Enables a user to transfer files. Provides access to files and directories.

TFTP (Trivial File Transfer Protocol)

A bare-bones version of FTP that does not provide access to directories.

With TFTP you can just send and receive files. Unlike FTP, TFTP

is not secure and sends smaller blocks of data.

HTTP (Hypertext Transfer Protocol)

Helps to browse internet with transmission of HTML and other Web documents.

HTTPS (Secure Hypertext Transfer Protocol)

Enables secure web browsing. A secure connection is indicated

(HTTPS) when the URL begins with https:// or when there is a lock symbol

at the lower-right corner of the web page that is being viewed.

SMTP (Simple Mail Transfer Protocol)

Sends e-mail across internet

POP3 (Post Office Protocol)

Received e-mails by accessing an internet server.

DNS (Domain Name System)

Resolves FQDN (Fully Qualified Domain Name) to IP addresses,

NFS (Network File System)

Enables users with different operating systems (for example, NT

and Unix workstations) to share files.