What is the most common data link layer protocol for a wired connection

I think the answer is The PPP (Point-to-Point Protocol).

It is the most common type of protocol that people use using a modem, a device or a router to have an internet connection. Here there two systems that establish a link to each other which is the point to point. The bits are transferred to a sender and a receiver. 

The common data link layer protocol for wired connection is point to point protocol (PPP) Which is a data link layer communication protocol used to establish a direct connection between two nodes.It connects two routers directly without any host or any other networking device in between.This protocol is used for a very basic level of connectivity providing data linkage between the computers.It is widely used for the heavier and faster connections necessary for broadband communications.

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