What is U?
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U is the standard unit of measurement for rack-mounted equipment. Racks can be used to house servers, hard drives, switches, routers, and other computer hardware. They are also used for mounting audio and video equipment. Standard racks are 24 inches wide, but vary in height. For this reason, the U unit measures how tall a rack-mountable hardware device is.
1U is equal to 1.75 inches. Therefore, a 1U piece of equipment is 1.75 inches tall and takes up one unit of rack space. A 2U device is 3.5 inches tall and takes up 2 units of rack space. Racks themselves are also measured in U. For example, a 10U rack could store 10 1U devices or 5 2U devices. It could also store 3 3U devices, with just enough space left over for your miniature Star Wars action figure.
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What is UDP?
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Stands for "User Datagram Protocol." It is part of the TCP/IP suite of protocols used for data transferring. UDP is a known as a "stateless" protocol, meaning it doesn't acknowledge that the packets being sent have been received. For this reason, the UDP protocol is typically used for streaming media. While you might see skips in video or hear some fuzz in audio clips, UDP transmission prevents the playback from stopping completely.
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What is Ultra DMA?
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This technology for transferring data between a computer's hard disk and memory was developed by Quantum and Intel. The maximum burst rate of an Ultra DMA hard drive is 33.3 MBps. The original DMA (Direct Memory Access) protocol could only transfer data at half that speed.
Thanks to Ultra DMA, programs can open faster and run more smoothly. This is because Utlra DMA can send more data to the memory in less time than the original DMA. Ultra DMA also has a built-in utility called Cyclical Redundancy Checking (CRC) that helps protect data integrity. So if you want a nice, fast hard drive, look for one that supports Ultra DMA.
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What is UML?
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Stands for "Unified Modeling Language." This is a programming language that is used for object-oriented software development. To organize program code more efficiently, programmers often create "objects" that are sets of structured data within programs. UML, which has been standardized by the Object Management Group (OMG), was designed for this purpose. The language has gained enough support that it has become a standard language for visualizing and constructing software programs.
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What is UNC?
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Stands for "Universal Naming Convention," not just the home of the North Carolina Tar Heels. UNC is a filename format that is used to specify the location of files, folders, and resources on a local-area network (LAN). The UNC address of a file may look something like this:
\\server-name\directory\filename
UNC can also be used to identify peripheral devices shared on the network, including scanners and printers. It provides each shared resource with a unique address. This allows operating systems that support UNC (such as Windows) to access specific resources quickly and efficiently.
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What is Unique Visitors?
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Unique visitor is a real visitor to a web site. Web servers record the IP addresses of each visitor, and this is used to determine the number of real people who have visited a web site. If for example, someone visits twenty pages within a web site, the server will count only one unique visitor (because the page accesses are all associated with the same IP address) but twenty page accesses.
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What is Unix?
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Also known as UNIX, though the letters do not stand for anything. The Unix operating system was first created in Bell Labs way back in the 1960s. It became popular in the 1970s for high-level computing, but not on the consumer level. Since a lot of Internet services were originally hosted on Unix machines, the platform gained tremendous popularity in the 1990s. It still leads the industry as the most common operating system for Web servers.
Still, Unix remains somewhat of an ambiguous operating system, as there are many different versions of it. Some examples include Ultrix, Xenix, Linux, and GNU, which, making things even more confusing, all run on a number of different hardware platforms. Most people do not ever need to use Unix, but computer geeks seem to have the need to use it as much as possible.
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What is Upload?
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When one computer sends information to another, it is called uploading.
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What is URL?
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A Uniform Resource Locator, URL, or Web address, is a standardized address for some resource (such as a document or image) on the Internet (or elsewhere). First created by Tim Berners-Lee for use on the World Wide Web, the currently used forms are detailed by IETF standard.
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What is USB?
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Stands for "Universal Serial Bus." USB is the most common type of computer port used in today's computers. It can be used to connect keyboards, mice, game controllers, printers, scanners, digital cameras, and removable media drives, just to name a few. With the help of a few USB hubs, you can connect up to 127 peripherals to a single USB port and use them all at once (though that would require quite a bit of dexterity).
USB is also faster than older ports, such as serial and parallel ports. The USB 1.1 specification supports data transfer rates of up to 12Mb/sec and USB 2.0 has a maximum transfer rate of 480 Mbps. Though USB was introduced in 1997, the technology didn't really take off until the introduction of the Apple iMac (in late 1998) which used USB ports exclusively. It is somewhat ironic, considering USB was created and designed by Intel, Compaq, Digital, and IBM. Over the past few years, USB has become a widely-used cross-platform interface for both Macs and PCs.
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What is User Agent?
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A user agent is the client application used with a particular network protocol; the phrase is most commonly used in reference to those which access the World Wide Web. Web user agents range from web browsers to search engine crawlers ("spiders"), as well as screen readers and braille browsers used by people with disabilities.
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What is Username?
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A username is a name that uniquely identifies someone on a computer system. For example, a computer may be setup with multiple accounts, with different usernames for each account. Many websites allow users to choose a username so that they can customize their settings or set up an online account. For example, your bank may allow you to choose a username for accessing your banking information. You may need to choose a username in order to post messages to a certain message board on the Web. E-mail services, such as Hotmail require users to choose a username in order to use the service.
A username is almost always paired with a password. This username/password combination is referred to as a login, and is often required for users to log in to websites. For example, to access your e-mail via the Web, you are required to enter your username and password. Once you have logged in, your username may appear on the screen, but your password is kept secret. By keeping their password private, people can create secure accounts for various websites. Most usernames can contain letters and numbers, but no spaces. When you choose a username for an e-mail account, the part before the "@" is your username.
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What is Utility?
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Utility programs, commonly referred to as just "utilities," are software programs that add functionality to your computer or help your computer perform better. These include antivirus, backup, disk repair, file management, security, and networking programs. Utilities can also be applications such as screensavers, font and icon tools, and desktop enhancements. Some utility programs help keep your computer free from unwanted software such as viruses or spyware, while others add functionality that allows you to customize your desktop and user interface. In general, programs that help make your computer better are considered utilities. And unlike water and electric bills, computer utilities don't send you a bill every month!
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