At which level does local and localhost communication work?

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When we talk about local and localhost, we usually refer to communication on the same computer. In this case, communication mainly occurs at the following levels:

1. Application Layer :

   • The starting point for communication is usually the application layer, which is the highest layer of the protocol stack. Applications such as web servers and clients (such as browsers) run on this layer and transmit data through lower-layer protocols.

2. Transport Layer :

   • Local communication will usually be through a transport layer protocol such as TCP or UDP. For example, when you visit in a browser http://localhost, you usually communicate with the web server on port 80 (or other designated port) on your local machine through the TCP protocol.

3. Network Layer :

   • Normally, local communication does not go through the network layer. However, if your application or system is configured to handle local communication through the network layer (for example, using the IP protocol), then the communication will pass through this layer.

4. Data Link Layer and Physical Layer :

   • For local communications, data typically does not pass through the data link layer and physical layer because these communications do not leave the local machine.

"localhost" usually refers to a special address on the local machine, usually corresponding to an IPv4 address 127.0.0.1or an IPv6 address ::1. When you localhostsend a request to, the request does not leave your machine, but is processed directly on your machine by the corresponding service (for example, a locally running web server).

localhostCommunication between local and Communications are not passed to the external network but are handled directly on the local machine, which is generally faster and more secure than communicating over the external network.