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Which application layer protocols use TCP and which use UDP?

In networking, different application layer protocols use either TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) depending on their requirements for reliability, speed, and connection-oriented services. Here’s a summary:

Protocols Using TCP

  1. HTTP (Hypertext Transfer Protocol): Used for transferring web pages and web content. Ensures reliable delivery of data between a web server and client (browser).
  2. HTTPS (HTTP Secure): The secure version of HTTP, which uses SSL/TLS to encrypt data transmitted over the network.
  3. FTP (File Transfer Protocol): Used for transferring files between a client and server. It requires reliable data transfer and connection-oriented services.
  4. SMTP (Simple Mail Transfer Protocol): Used for sending email messages between servers. TCP ensures reliable message delivery.
  5. POP3 (Post Office Protocol version 3): Used by email clients to retrieve emails from a server. It requires a reliable connection.
  6. IMAP (Internet Message Access Protocol): Used by email clients to access and manage emails on a server. It also requires a reliable connection.
  7. Telnet: Provides a text-based interface to interact with remote computers. TCP ensures a reliable connection for command and control.
  8. SSH (Secure Shell): Used for secure remote login and command execution. It provides a secure, encrypted connection.

Protocols Using UDP

  1. DNS (Domain Name System): Resolves domain names to IP addresses. UDP is used for its speed, although it may sometimes use TCP for larger data.
  2. DHCP (Dynamic Host Configuration Protocol): Assigns IP addresses to devices on a network. UDP is used for its low overhead and speed.
  3. TFTP (Trivial File Transfer Protocol): A simple file transfer protocol used primarily for transferring small files. It uses UDP for simplicity and reduced overhead.
  4. SNMP (Simple Network Management Protocol): Used for network management and monitoring. UDP is used for its simplicity and efficiency.
  5. VoIP (Voice over IP): Includes protocols like SIP (Session Initiation Protocol) and RTP (Real-Time Transport Protocol) used for voice communication. UDP is preferred due to its lower latency, which is crucial for real-time communication.
  6. Streaming Media: Protocols such as RTSP (Real-Time Streaming Protocol) and RTP are used for streaming audio and video. UDP is preferred for its lower latency, although it does not guarantee delivery.

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