A rack is a metal support designed to house electronic, computer and communications equipment. The measures for the width are normalized to be compatible with most equipment manufacturers. They are also called racks, cabinets, cabinets or closets. Each column has holes at regular intervals called U rack units (Pictured: 4) grouped in threes. The height (Pictured:5) of the racks is standardized and external dimensions of 200 mm by 200 mm. Being normal that from 4U to 46/47U height width types (Pictured: 7). Standard 600 mm or 800 mm Types of background (Pictured: 6) The depth of the frame is not standardized, as this flexibility is granted (Pictured: 8) to the equipment. The most common are: - 450 mm - 600 mm - 800 mm - 900 mm - 1000 mm - 1200 mm Type 19-inch rack can find various types of 19-inch rack. Rack Mural (Pictured: 2): Used to accommodate electronic network. They are the smallest and are anchored to wall. Rack Pie (Pictured: 1): They are used primarily for servers, UPS and network electronics. Open Rack (Pictured: 3): Open Rack Racks are available only modelsstructure, eliminating doors and other accessories.

One hertz is one cycle per second, meaning repeating cycle as an event. For example, hertz is applied physics measuring the number of times for a second wave (either acoustic or electromagnetic) is repeated or can be applied, among other uses, to ocean waves that reach the Beach vibrations per second or a solid. The quantity that measures the frequency hertz is called,in this regard, the inverse of the period. One hertz is an oscillation frequency of suffering a particle over a period of one second.

The RJ-11 is mainly used to link telephone networks connector. It is small and has four contacts measures to support 4-way 2 cables. It is the most widely used globally for connecting conventional telephones, which generally tend to use only the two central threads to a single line or a twisted pair connector. And the four wires are used only for telephony equipment special using double line or two telephone pairs. After crimp the cable, it is almost impossible to disarm the RJ-11 without causing its deactivation.

The RJ12 connector is a phone that has the same dimensions as the RJ11 connector, the difference is that it has 6 contacts, instead of 4.

This connector is for a cable crimp wire 6 and has 6 positions (where the blades are housed) and 6 contacts (6P6C), implying that all are used.