What is the purpose of the Ethernet header?

The Ethernet header serves multiple purposes in network communication, but one of its primary functions is to identify the sender and receiver of the data frame. Within the Ethernet header, you'll find essential fields such as the source MAC (Media Access Control) address and the destination MAC address. These addresses are crucial because they ensure that the data sent over the network reaches the correct device.

By using the MAC addresses, each network interface card (NIC) can be uniquely identified within a local area network. This identification process is fundamental for successful data transmission, as it allows devices to communicate with each other effectively. In essence, the Ethernet header acts like a mailing address on a letter, guiding the data to its intended recipient while also identifying who sent it.

While the header may include other information that supports functions like error detection and frame size indication, the primary role of the Ethernet header revolves around establishing the link between sender and receiver on a data link layer.