Internet Protocols C1 chap 2

Internet Protocols

TCP/IP

  • Protocols govern network communication, defining data format and order.
  • TCP divides data into packets, numbers them, and reassembles them at the destination.
  • IP is responsible for transmitting data packets, adding destination addresses, and selecting the best path.
  • Data transmission involves data division, IP addressing, routing, and reassembly.
  • TCP/IP protocol stack: Includes Application, Transport, Network, Data Link, and Physical layers for both sender and receiver.

IP Addresses

  • IP addresses are numerical addresses that identify devices on a network.
  • ICANN assigns IP addresses through ISPs.
  • IPv4: 32-bit address, four 8-bit numbers (octets) separated by periods, ranging from 0.0.0.00.0.0.0 to 255.255.255.255255.255.255.255.
  • IPv6: 128-bit address, eight 16-bit numbers separated by colons, ranging from 0:0:0:0:0:0:0:00:0:0:0:0:0:0:0 to FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFFFFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF.

Domain Name System (DNS)

  • Domain names are used because IP addresses are difficult to memorize.
  • A Fully Qualified Domain Name (FQDN) includes all domain levels, delimited by dots.
  • DNS hierarchy: Root domain, top-level domain (TLD), registration name, hostname.
  • TLDs: generic (gTLDs) based on organization type or country code (ccTLDs) based on location.
  • DNS servers translate domain names into IP addresses through a process called "name resolution."

Uniform Resource Locator (URL)

  • A URL identifies the specific location of a resource on the Internet.
  • Components of a URL: network protocol, FQDN/IP address, port number, path.
  • Network protocol: Set of rules used for network communication.
  • FQDN/IP address: Unique identification of a host on a network.
  • Port number: Identifies a specific application on a host.
  • Path: Specific location of a resource related to the root directory of the host.

Network Protocols

  • HTTP and HTTPS are used for transferring data over the internet.
  • HTTPS: A secure version of HTTP that uses SSL/TLS encryption for secure data transmission.
  • SMTP: Used to send emails to email servers.
  • IMAP and POP3: Used by email clients to retrieve emails from an email server.
  • POP3: Downloads emails to a local computer and typically deletes them from the server.
  • IMAP: Keeps emails on the server, allowing access from multiple clients and synchronization across devices.