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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.