5 Tools Everyone in the 프리서버 Industry Should Be Using

1. What is the meaning of virtual windows? Virtual windows is about to install another Operating System on an Operating System, example you install Ubuntu Linux on Microsoft Windows XP. One of much Virtual Operating System or other name is Virtual Machine application is named Virtual Box, it's free to use because it is freeware software you can download Virtual Box without cost. Virtual Box Download If you want to download Virtual Box just find it on Google the best search engine on the world and download it. The size of Virtual Box installer is about 32 Mb. Installing Virtual Box on your computer If you have download the application, now you need to install it to your computer. This is the step how to install Virtual Box on your computer: 1. Open Virtual Box Setup, example VirtualBox-2.0.2-36488-Win_x86.exe 2. Follow the installing instructions then wait, less than a 2 minute the dialog box titled "Software Installation" is displayed then click "Continue Installation" this dialog box displayed not just 1 time. 3. Then click finish, and restart your computer. Using Virtual Box 1. First You need to prepare the Operating System CD Installer to use the application. For example Ubuntu Linux. 2. Open the software on the start menu (if you have to install it). 3. The welcome screen will displayed on first time use, insert your Name and E-mail to register (do this following action if you connected to the internet but if you not connected to the internet just click Cancel). 4. Now, the second step we will make some Virtual Disk, click File > Virtual Disk Manager. 5. Click New button. 6. Click Next > Select Image Type then Next > Type the Name of your Virtual Disk, Example My Disk.vdi, set the Image Size you want > Click Next button.

2. 7. Finish > Click OK button. 8. Now the third step is making Virtual Machine (the point of this article), Click New button > Next > select your Virtual Machine Name and Type, for example My Ubuntu Linux and find named Ubuntu on the "OS Type". 9. Click Next button > set the memory of Virtual Machine then click Next. I set 512 Mb. 10. Select the Virtual Disk to use, example My Disk.vdi then click Next. 11. Click finish button, now you Virtual Machine is created successfully. 12. Now the last step is Installing Operating System (Ubuntu Linux). 13. Right click on the My Ubuntu Linux Machine and click setting > select CD/DVD-ROM > check "CD/DVD Drive" > select "Host CD/DVD Drive" If you want to install Ubuntu Linux via your CD/DVD Drive or select "ISO Image File" if you using ISO file. Then click OK 14. Click start button to start installing Ubuntu Linux > click OK and follow the installing steps to installing Linux Ubuntu. 15. If you have install the Operating System then you have finished making Virtual Machine The Network Time Protocol (NTP) is a protocol designed purely for the transfer of accurate time around a computer network. The protocol allows network clients to accurately synchronise system time with a precise reference clock. This article describes what a NTP server is, how it operates, and why modern organisations need synchronised network time. A NTP server is a network device that obtains accurate time information from an external timing reference. Accurate time is maintained internally by the device and provided to any network client that requires it. Any device on a network can synchronise it's internal system time to a NTP server. In this manner whole networks of computer systems can maintain synchronisation with an accurate reference. NTP is a hierarchical protocol. At the highest level is a stratum1 primary reference NTP time server. A stratum 1 server obtains accurate time from an external hardware clock. A stratum 1 server is the most accurate reference, since it synchronises directly to a precise external source of time. Time servers lower down the hierarchy synchronise to the stratum above and provide consistently less accuracy. However, using a hierarchical system allows multiple time servers to take workload away from the most accurate references and prevents them from becoming swamped with requests for time. A number of external timing references, or hardware clocks, are available that provide accurate time. The Global Positioning System, GPS, is by far the most popular source of time for external reference clocks. The GPS constellation of satellites each has super-accurate synchronised atomic clocks on board to provide precise timing information. GPS timing information can be received worldwide, provided an antenna can be shown a good view

3. of the sky. National radio time and frequency broadcasts are also a good source of accurate time. Radio time signals can generally be received by an indoor antenna within the broadcast range of the transmission. A number of broadcasts are available around the world including; MSF (UK), DCF-77 (Germany), WWVB (USA) and JJY (Japan). Many NTP time servers also contain precision backup reference clocks in order to maintain accurate time during signal outages. A backup reference clock provides extended holdover while external reference clock time is unavailable. A number of backup timing solutions are available, the most accurate, and expensive, being a Rubidium Oscillator. These highly stable oscillators maintain very accurate holdover for extended periods of time. Good price / performance alternatives are OCXO and TCXO oscillators. An OCXO, Oven-Controlled Crystal Oscillator, is a crystal oscillator that is housed in a very small oven to maintain constant temperature. Since the greatest cause of drift in crystals is temperature variation, OCXO's attempt to minimise drift by maintaining a constant temperature. TCXO, Temperature-Controlled Crystal Oscillators, work on a similar principle. However, rather than maintain a constant temperature, they speed up or slow down slightly to compensate for any temperature variation. These various oscillators are disciplined by the GPS time signal to provide a very stable time output to maintain holdover during signal outages. This allows networks to remain synchronised when external reference clock synchronisation is lost. Most modern computer operating systems provide integrated NTP client software, which allow synchronisation to a time server. LINUX and UNIX operating systems have a freely available GNU public licence NTP client available. The Microsoft Windows operating system utilises the 'Windows Time' service to provide NTP synchronisation. Additionally, Novell also provides loadable modules for synchronisation of Netware servers. Many modern computing applications are distributed systems operating across a large number of individual machines. Without synchronisation of cooperating devices many problems can arise. Event logging may not provide a true representation 버버버버버 of when a specified event occurred. Synchronised time is required to ensure time-stamped transactions are generated in the correct order. Many modern computer applications require accurate timestamps for correct operation. NTP is used throughout the Internet to synchronise the network infrastructure. It is also adopted by most organisations to provide an accurate, traceable, source of time for networked computing equipment. NTP is the 'de facto' standard protocol for network time distribution.