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Application Layer - Seventh Layer in OSI Reference Model

Application Layer is the seventh layer in Open System Interconnection (OSI) Reference Model. The function of the Application layer is to present data to users by enabling direct interaction between user and software applications. In simple words, the major function of the Application layer in the OSI Reference Model is to provide a user interface. The user interface can be either a command line based or GUI based. GUI based user interface is used in a web browser and Command Line Interface(CLI) is used in Routers and Switches (IOS high-end Routers and Switches).

Application Layer Protocols

A set of protocols are working on the application layer. These application layer protocols are classified into two.

  1. Common Application Specific Elements (CASE)
  2. Specific Application Specific Elements (SASE)

The major Application Layer protocols are:

  1. Telnet
  2. File Transfer Protocol (FTP)
  3. Simple Mail Transfer Protocol (SMTP)
  4. FTAM
  5. HTTP
  6. DHCP
  7. NFS
  8. POP3
  9. NNTP
  10. IRC

OSI Seven Layer Structure
  1. Physical layer

  2. Data link layer

  3. Network layer

  4. Transport layer

  5. Session layer

  6. Presentation layer

  7. Application layer

List of Application Layer Utilities

The major Application Layer utilities are.
  1. Address Resolution Protocol (ARP)

  2. Netstat

    Netstat works in the application layer. To learn more about this application layer utility, visit the link below.
    Netstat -A Command Line Tool

  3. Ping

  4. Tracert

  5. FTP and TFTP

  6. Hostname

  7. Whois

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Alex George
Alex George has Engineering graduation in Computer Science and an MBA in Finance. He had been working as a senior Network Engineer for ten years. His specialization is in Cisco products. Traveling is one of his hobbies and visited various places as part of his onsite work. He visited different places as part of his onsite work like New York, Dubai, London, etc. Right now Alex is a director of one of the leading career development firms in India, which trains students for UPSC, SSC, and PSC examinations. He guides a lot of students to get selection for various prestigious institutions like CBI, Income Tax Department, etc. Alex George is a stock market investor and a very active intraday trader. Engineering Background: He has a B.Tech in Computer Science and Engineering and passed different network and security courses like CCNA, CCNP (Security), CEH, and various Microsoft certifications. Finance Background: Alex has an MBA in Finance. He is an active intraday trader and a Share Market Investor. Webmaster Skills: Alex is a blogger since 2004. He has a working knowledge of HTML, CSS, PHP, and JavaScrip.