Internet Protocols to Know for AP Computer Science Principles

Internet protocols are essential for how devices communicate online. They manage everything from data transfer to secure connections, making the Internet functional and user-friendly. Understanding these protocols is key to grasping the broader concepts in AP Computer Science Principles.

1. TCP/IP (Transmission Control Protocol/Internet Protocol)

   • TCP/IP is the foundational protocol suite for the Internet, enabling communication between devices.
   • It consists of two main protocols: TCP, which ensures reliable data transmission, and IP, which handles addressing and routing.
   • TCP breaks data into packets, manages their delivery, and reassembles them at the destination.

2. HTTP (Hypertext Transfer Protocol)

   • HTTP is the protocol used for transferring hypertext (web pages) over the Internet.
   • It operates on a request-response model, where a client (browser) requests resources from a server.
   • HTTP is stateless, meaning each request is independent and does not retain session information.

3. HTTPS (Hypertext Transfer Protocol Secure)

   • HTTPS is the secure version of HTTP, using encryption (SSL/TLS) to protect data during transmission.
   • It ensures data integrity, confidentiality, and authentication between the client and server.
   • HTTPS is essential for secure online transactions and protecting sensitive information.

4. DNS (Domain Name System)

   • DNS translates human-readable domain names (like www.example.com) into IP addresses that computers use to identify each other.
   • It acts as the Internet's phonebook, allowing users to access websites without needing to remember numerical IP addresses.
   • DNS operates through a hierarchical structure, with multiple levels of servers to resolve queries.

5. IP addressing (IPv4 and IPv6)

   • IP addresses are unique numerical labels assigned to each device on a network, enabling identification and communication.
   • IPv4 uses a 32-bit address format, allowing for approximately 4.3 billion unique addresses, which are nearly exhausted.
   • IPv6, the successor to IPv4, uses a 128-bit address format, vastly increasing the number of available addresses.

6. FTP (File Transfer Protocol)

   • FTP is a standard network protocol used to transfer files between a client and a server over the Internet.
   • It supports both anonymous and authenticated access, allowing users to upload and download files securely.
   • FTP operates on a client-server model and can use either active or passive modes for data transfer.

7. SMTP (Simple Mail Transfer Protocol)

   • SMTP is the protocol used for sending and relaying email messages between servers.
   • It operates primarily over TCP port 25 and is responsible for the delivery of outgoing mail.
   • SMTP is not used for retrieving emails; it only handles the sending process.

8. POP3 (Post Office Protocol version 3)

   • POP3 is a protocol used by email clients to retrieve emails from a mail server.
   • It downloads emails to the client and typically deletes them from the server, allowing offline access.
   • POP3 is simple and effective for users who access their email from a single device.

9. IMAP (Internet Message Access Protocol)

   • IMAP is a protocol that allows email clients to access and manage emails directly on the mail server.
   • It supports multiple devices, enabling users to view and organize their emails without downloading them.
   • IMAP retains emails on the server, allowing for synchronization across devices.

10. UDP (User Datagram Protocol)

    • UDP is a connectionless protocol used for transmitting data without establishing a connection.
    • It is faster than TCP but does not guarantee delivery, order, or error correction, making it suitable for real-time applications.
    • UDP is commonly used for streaming media, online gaming, and voice over IP (VoIP) services.