(i) The RJ-21 connector has 50 pins with 25 pins at one end an 25 pins at the other end. It is typically used for data communication.
(ii) It is also called a champ connector (or) Amphenol connector. The Amphenol is a connector manufacturer.

(i) This cable is different from coaxial and twisted cables. They are placed in deep underground to avoid any damage to the cables.
(ii) It is of strands of glass and pulse of light is used to send the information.
(iii) They are mainly used in wireless Area Networks (WAN).

(i)The cable is used to transfer the information in 10 Mbps. They are too big to carry and replace.
(ii) The cable is divided into thinnet and thicknet cables. They are very difficult to install and maintain.
(iii) These cables have a copper wire inside and insulation is covered on the top of the copper wire to provide protection to the cable.

(i) Wireless networks enable more devices including mobiles sharing the resources and Internet connections remotely. Example: Bluetooth, WiFi, Infrared.
(ii) But compared to wireless networks, wired networks maintain a faster internet speed and more secure. Example: Routers, Switches may be used to increase the number of systems to be interconnected.
(iii) Wired networks for larger area are more expensive. Wired networks are still used widely in the offices where we need increased speed and secured connections.

(i) RJ45 connector has 8 small jack inside to connect 8 small wires of the patch-cable.
(ii) The 8 cables are in 8 different colors. There are two wiring schemes totally.
(iii) This wiring schemes specifies how the wires to be connected with RJ45 connector. The two wiring schemes are WT-568A and WT-568B.

(i) In the roll-over cable, the coloured wires are reversed on other end. The coloured wires are in the opposite sequence at either end of the cable.
(ii) The pins on one end are connected with other end in reverse order (i.e. pin 1 to 8, 2 to 7, 3 to 6, 4 to 5,5 to 4,6 to 3, 7 to 2,8 to 1).

1. It is a type of null-modem cable that is often used to connect a device console port to make programming changes to the device.
2. The roll-over wiring has opposite pin arrangements, all the cables are rolled over to different arrangements. Also known as Yost cable (or) Console cable.

(i) This is a simple physical connection used in printers, computers, and other network interfaces.
(ii) These wires are mostly used for connecting PC/NIC card to a hub.

(i) The RJ-21 connector has 50 pins with 25 pins at one end an 25 pins at the other end. It is typically used for data communication.
(ii) It is also called a champ connector (or) Amphenol connector. The Amphenol is a connector manufacturer.

(i) Straight-through: The coloured wires are in the same sequence at both ends of the cable.
(ii) Cross-over: The first coloured wire at one end of the cable is the third coloured wire at the other end of the cable.
(iii) Roll-over: The coloured wires are in the opposite sequence at either end of the cable,

Computers can be connected on the network with the help of wired media such as unshielded twisted pair 
(i) Shielded Twisted pair
(ii) Co-axial cables and Optical fibre
(iii) Wireless media (Infra Red, Bluetooth, WiFi)