Video Description

Application Layer- Web Services

  • HTTP

    • Hyper Text Transfer Protocol

    • Supports web services

    • Uses port number 80

    • The secure version is HTTPS

    • HTTPS uses port number 443

    • Transfers text, images, and hyper links

  • HTTPS

  • File Sharing Services/File transfer

    • FTP

      • File Transfer Protocol

      • Uses port number 21

      • Built=in in MS Windows Operating Systems

      • Many 3rd party programs

      • Web browser works as FTP client

    • TFTP

    • Network File System

  • Mail Services

    • SMTP

      • Common language used by the majority of mail servers

      • Send messages back and forth to other mail servers or email clients

    • POP3 "Post Office Protocol version 3"

      • Collects email messages from the mail server

      • Download messages on the machine

      • User can work offline

      • Saves quota on the server

    • IMAP4 "Internet Message Access Protocol version 4"

      • Retrieves the message header only
  • DNS Services

    • Domain Name System DNS resolves Domain Name into IP Address

Course Modules