Definition of "loopback" []

• The routing of a signal, data stream, etc. from its origin back to the origin, primarily as a means of testing the transmission or transportation infrastructure. (noun)

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• "Configures the device to perform DTE (Data Terminal Equipment) loopback, which is a diagnostic test of the internal CSU/DSU and the local DTE."
• "Configures the device to perform local loopback, which is a diagnostic line test which forces the device's CSU to loop data received from the network back out to the network. remote"
• "Instead, I'm going to use what's known as the loopback address, which every server translates to 127.0.0.1."