RJ45
RJ11
The 8P8C (eight-position, eight-contact) interface is the standard interface for RJ45 connectors. As the name implies, it has eight positions and eight contacts, which perfectly matches the 45-pin design of the RJ8 connector. This interface is commonly found on computers, routers, and other network equipment.
While similar to the RJ45, the RJ11 interface is significantly smaller and is often used for telephone wiring. It has a six-position, four-contact (6P4C) configuration. While an RJ11 plug can be plugged into an RJ45 interface, the reverse is not true due to the larger size of the RJ45 plug. This is an important distinction to remember to avoid potential damage to network equipment.
