Figure illustrates the different connection types used by each physical layer implementation. The registered jack (RJ-45) connector and jack are the most common. RJ-45 connectors are discussed in more detail in the next section.

In some cases the type of connector on a network interface card (NIC) does not match the media that it needs to connect to. As shown in Figure , an interface may exist for the 15-pin attachment unit interface (AUI) connector. The AUI connector allows different media to connect when used with the appropriate transceiver. A transceiver is an adapter that converts one type of connection to another. Typically, a transceiver converts an AUI to RJ-45, coax, or fiber optic connector. On 10BASE5 Ethernet, or Thicknet, a short cable is used to connect the AUI with a transceiver on the main cable.