DNS Server and DNS Server Roles Overview Before DNS, HOSTS files were used to resolve host names to IP addresses. The HOSTS files were manually maintained by administrators. The HOSTS file was located on a centrally administered server on the Internet. Because of the shortcomings of the HOSTS files, DNS was designed and introduced. From the days of Windows NT Server 4.0, DNS has been included with the operating system. DNS is a hierarchically distributed and scalable database. DNS provides name registration, name resolution and service location for Windows 2000 Read More

Pulse Code Modulation (PCM) was pioneered by the British engineer Alec Reeves in 1937. The first transmission of a message using PCM was the SIGSALY voice encryption equipment used in high-level Allied communications during World War II starting in 1943. The original primary application for PCM was to convert analog signals into digital format by taking samples of wave forms that fall within 8 to 192 KHz and converting them into a digital number 8 to 24 bits long. In short, PCM refers to the technique of digitalizing an analog Read More

A PDF (Portable Document Format) file is a word processing document in which text, images, and notes can be organized and displayed in the form of an electronic book. PDF files allow users to highlight text, organize content in the form of page numbers and chapters, and insert notes, fonts, and images. They differ from other word processing document types due to their lack of dependency on any particular application, software, or operating system. Adobe Systems created the PDF format in 1993 and it has been in popular use ever Read More

A capacitor is used to store energy so that it can provide power to any kind of electrical appliance when it is needed. Over time, though, the capacitor does begin to wear out and when this happens, its effectiveness in powering the appliance can diminish. Therefore, conducting a simple test on the capacitor can provide the necessary insight into whether the capacitor is worn out or if there is something else wrong with the appliance. Testing a Capacitor Before doing anything with the capacitor, disconnect the appliance from the electrical Read More

Potassium alum is also known as potash alum, tawas, and alum (its common name). The specific compound is the hydrated potassium aluminum sulfate and it is commonly found in deodorant, aftershave treatments, fireproof textiles, baking powder, and used in leather tanning and water purification. It is soluble and liquefies when heated. Potassium alum is colorless in crystal form and is completely translucent when 100% pure, making it popular amongst those who collect minerals in the wild. Potassium Alum’s Characteristics Potassium alum is very soluble in water and becomes a porous, Read More

TTF files are files that used a font developed by Apple in the 1980s to compete with Adobe's Type 1 Fonts. Since then, TTF has become one of the most common fonts for both Mac OS and Windows. However, other fonts have also been used–OpenType and ClearType. Regardless, many computers are able to open TTF files so long as they have the proper font installed.  The first step to open a TTF file is to move it to your hard drive or insert a CD that has the file on Read More

Modulation is the process of varying some characteristic of a periodic wave with external signals. Modulation is utilized to send an information bearing signal over long distances. Radio communication superimposes this information bearing signal onto a carrier signal. These high frequency carrier signals can be transmitted over the air easily and are capable of traveling long distances. The characteristics (amplitude, frequency, or phase) of the carrier signal are varied in accordance with the information bearing signal. In the field of communication engineering, the information bearing signal is also known as Read More

An adhesive remover is a chemical that can break the chemical bonds of adhesives. There is a wide variety of adhesive removers because there are many different types of adhesives. Each adhesive on the market has a slightly different formula/chemical structure. Therefore, an adhesive remover must be specifically formulated to break down each adhesive. Adhesive removers can either be toxic or nontoxic and can range in texture depending on the type of adhesive it was made to remove. Toxic Adhesive Removers Solvent-based Solvent-based adhesive removers are the most toxic but Read More

The computer BIOS (Basic Input/Output System) is found on Windows computers. The BIOS is the first application launched during the computer’s boot process. The program is used to check for and initialize computer hardware during the start-up process prior to passing control of the computer to the operating system. Unlike the OS that is normally saved on the local hard drive, a computer’s BIOS is stored as updateable firmware on a ROM (Read Only Memory),  EEPROM (Electrically Erasable Programmable Memory), or flash memory chip on the motherboard. When was BIOS Read More

Cisco uses a proprietary cable pinout for their serial console cables. Note: Pinout or pin-out is a term used in electronics to describe how an electrical cable is wired, or the function of each wire (pin) in a connector. Given below are the pinout details for a Cisco cable. 9-pin Cisco Cable Cable Pinout Signal DB9F RJ45 Receive Data 2 3 Transmit Data 3 6 Data Terminal Ready 4 7 Ground 5 4 Ground 5 5 Data Set Ready 6 2 Request to Send 7 8 Clear to Send 8 Read More