Glossary

Review the definitions for terms used across Cloudflare’s Spectrum documentation.

Term	Definition
ACK (Acknowledge)	The final step in the TCP three-way handshake, confirming the establishment of a connection.
FTP (File Transfer Protocol)	A standard network protocol used for transferring files from one host to another over a TCP-based network.
FTPS (File Transfer Protocol Secure)	An extension of FTP that adds support for the Transport Layer Security (TLS) or Secure Sockets Layer (SSL) cryptographic protocols.
layer 3	The network layer in the OSI model, responsible for logical addressing, routing, and forwarding of data between devices on different networks.
layer 4	The transport layer in the OSI model, managing end-to-end communication, error-checking, and flow control.
MQTT (Message Queuing Telemetry Transport)	A lightweight, publish-subscribe messaging protocol often used for communication in the Internet of Things (IoT) and other resource-constrained scenarios.
OSI model (Open Systems Interconnection model)	A conceptual framework that standardizes the functions of a telecommunication or computing system into seven abstraction layers.
proxy protocol	A protocol used by network proxies to convey client connection information to the destination server, facilitating proper handling of client requests.
reverse proxy	A server that handles requests on behalf of clients, forwarding them to backend servers and managing tasks like load balancing and security.
SFTP (Secure File Transfer Protocol)	A secure file transfer protocol that uses the Secure Socket Shell (SSH) protocol for encryption and authentication.
SMTP Server (Simple Mail Transfer Protocol Server)	A server responsible for sending, receiving, and relaying email messages over a network, following the SMTP protocol.
SYN (Synchronize)	The initial step in establishing a TCP connection, where a device requests a connection with another by sending a SYN packet.
SYN-ACK (Synchronize-Acknowledge)	The second step in the TCP three-way handshake, where the server responds to a SYN request with a SYN-ACK packet.
TCP (Transmission Control Protocol)	A connection-oriented protocol in the transport layer of the Internet Protocol Suite, providing reliable and ordered delivery of data between devices.
UDP (User Datagram Protocol)	UDP (User Datagram Protocol) is a connectionless transport layer protocol that provides fast and lightweight data transmission between devices on a network, prioritizing speed over reliability.