prtocols pt 2

• Contents of this topic

  • Basics
  • Topologies
  • Connectivity
  • Protocols
  • Routing
  • DNS
• Network protocol


  A set of rules governing the communication between devices on a network
• TCP/IP 5-layer protocol stack model

  1. Physical layer

  2. Data link layer

  3. Network layer

  4. Transport layer

  5. Application layer
• TCP


  Transmission Control Protocol
• IP


  Internet Protocol
• HTTP


  Hypertext Transfer Protocol - A client-server method of requesting and delivering HTML files
• HTTPS


  Hypertext Transfer Protocol Secure
• FTP


  File Transfer Protocol
• POP


  Post Office Protocol - Used by email clients to retrieve email from a mail server
• IMAP


  Internet Message Access Protocol - Used by email clients to retrieve email from a mail server, and to manage remote mail boxes. Better than POP.
• SMTP


  Sends mail to a mail server
• DNS


  A distributed database (available widely) that matches IP addresses to computer system resources with a URL (web pages and more)
• How DNS servers and IP addresses work

  1. DNS server contains list of domain names and corresponding IP addresses

  2. Web site address typed into browser

  3. Browser checks local host file for IP address

  4. Local DNS server queried for IP address

  5. If not found, query passed to higher level DNS servers

  6. Full address resolved, IP address passed to browser

  7. Browser connects to IP address and downloads website
• Controversial political websites may have the same site but move the IP address at which they can be found frequently to different countries to remain beyond legal sanction
• You can find the IP address of any website by using a tool like http://ipinfo.info/html/ip_checker.php