虚拟空间
虚拟主机[1]（Virtual Host Virtual Server）是使用特殊的软硬件技术，把一台计算机主机分成一台台"虚拟"的主机，每一台虚拟主机都具有独立的域名和IP地址（或共享的IP地址），具有完整的Internet服务器功能。在同一台硬件、同一个操作系统上，运行着为多个用户打开的不同的服务器程序，互不干扰；而各个用户拥有自己的一部分系统资源（IP地址、文件存储空间、内存、CPU时间等）。虚拟主机之间完全独立， 在外界看来， 每一台虚拟主机和一台独立的主机的表现完全一样。
虚拟主机技术的出现，是对Internet技术的重大贡献，是广大Internet用户的福音。由于多台虚拟主机共享一台真实主机的资源，每个用户承受的硬件费用、网络维护费用、通信线路的费用均大幅度降低，Internet真正成为人人用得起的网络！现在，几乎所有的美国公司(包括一些家庭)均在网络上设立了自己的WEB服务器，其中有相当的部分采用的是虚拟主机！
有些公司牛会自己买服务器，主机托管，或者服务器租用，也就是花钱把自己的服务器（好点的电脑而已）放在网通，电信这样的通信单位，让全世界的人可以访问你那台电脑。
■ 虚拟主机的硬件条件
试用：虚拟主机服务提供商一般会在用户购买其服务之前提供几天的试用时间，你完全可以在这几天的时间里了解虚拟主机的性能，给自己的网页和电子邮件挑选到一个合适的“大家庭”。
速度：使用电信骨干线路的、配置有约100个用户的虚拟主机，其网速肯定要比那些采用ADSL等低速线路连接的独立主机要快得多。
稳定性：当然，除了速度，我们还要注意网络环境的稳定性和安全性，比如服务商是否采用了思科、3Com的路由器连接到网络，是否购买了网关防火墙，是否有专人全天24小时监视来自网络的各种攻击……只有具备了上述条件的主机服务商才是我们选择的目标。
有些虚拟主机服务商随便找条低带宽的线路，再东拼西凑一些设备，找两个懂得调试Windows 2000的技术人员，然后就仓促上马提供服务。就算其价格再便宜，我们也不推荐使用。
服务稳定性源于服务商的基础设施。配置较高档的服务器，配有冗余设备、RAID卡等；有保证电源输入稳定的UPS、应急发电机；有保持恒温、恒湿的设备等等。当然，这些硬件设施，有时我们是不可能亲眼看到的。所以，购买之前通过多种途径（比如服务商的网站）多了解服务商的情况非常重要！毕竟，知己知彼，才能找到适合的主机！
■ 你需要多大的空间
虚拟主机服务器提供硬盘空间的类型分为独立Web空间、数据库空间、独立邮局空间等。虚拟主机空间的大小主要依据发布信息的多少。如果你的网站包含有10到150个左右的页面，每页算上相关图片，有100多KB，那你租用60MB的空间就差不多了。如果页面在几百页以上，并且需要有数据库支持，那你需要的相应空间应该在100MB到200MB之间。实际所需空间不足时可以再补差价向服务商申请增加空间大小；若一开始购买空间很大，可总也用不上那么多，退也退不掉，无疑是浪费金钱。
■ 虚拟主机的软件条件
虚拟主机的服务器一般采用Windows 2000（NT）和UNIX（linux）两种服务器操作系统，两者各有所长。数据库空间也分为两类：Windows 2000平台的 IIS 5.0/Access数据库空间和Linux平台的MySQL/PHP数据库空间。不过笔者个人还是比较倾向于选择Unix（linux），但是对于经常调用各种数据库且需要进行ASP网页设计的公司用户而言，则只能采用Windows 2000平台，UNIX系统支持的是PHP。
■ 地点和价格
服务器存放的地点也是选购时一定要仔细考虑的。如果网站的信息宣传范围在国外，那租用在美国的虚拟服务器是最佳选择，因为美国的网络带宽最大；如果宣传的范围主要在国内，那就租用放在国内电信节点的服务器为最好。对于价格，大家都是很敏感的。一些电信旗下的服务商价格会比较高，不过现在随着诸多虚拟主机服务商的崛起，虚拟主机的价格现在已经低了很多。
■ 售后服务
如“无法创建电子邮箱”、“主页无法访问”等等常见的售后问题，大概是不少拥有虚拟主机的朋友经常遇到的。有的服务商将销售放在首位，售后服务不是很完善，如只在首页做了邮箱设置方法、FTP设置方法以及技术问题的“伊妹儿”链接就完事了。而标榜的服务热线是服务商本地的电话，若外地朋友遇到问题打长途还得自己买单。具有本地售后服务支持、全国免费800售后电话支持的公司，无疑让我们在选购之前就放心了不少。购买之前可以装成客户询问一些问题、留意一下服务商的售后服务质量及态度，售后服务出色的虚拟主机在以后使用时会轻松很多。
Virtual Host (Virtual Host Virtual Server) is the use of special hardware and software technology, to a computer host Taiwan and Taiwan is divided into one "virtual" host, each virtual host has a separate domain name and IP address (or IP sharing address), with a complete Internet server functionality. On the same hardware, same operating system, running for multiple users to open a different server process, non-interfering; and individual users have their own part of system resources (IP address, file storage space, memory, CPU time ). Between virtual hosts is completely independent, outside view, each virtual host and a host of independent performance of the same.
Virtual host technology, Internet technology is a significant contribution to the vast number of Internet users of the Gospel. As a result of multiple virtual hosts to share a true host of resources, each user to bear the cost of hardware, network maintenance costs, the cost of communication lines are significantly reduced, Internet truly become affordable for all the networks! Now, almost all American companies (including some families) are on the network to set up its own WEB server, which has a considerable part is used in virtual host!
Some companies will buy their own cattle servers, hosting, or server rental, that is, spend money to its own server (a computer only good point) on Netcom, telecommunications units such as communication, so that people all over the world can access your Desk computer.
■ Virtual Console hardware requirements
Try: virtual host service provider will normally be the user's purchase of its services to provide a few days before the trial period, you can be in these days of time to understand the performance of the virtual host to their own Web pages and e-mail to a suitable selection "extended family."
Speed: the backbone of the use of telecommunications lines, about 100 users to configure the virtual host, and its speed surely than those who used low-speed connections such as ADSL independent host much faster.
Stability: Of course, in addition to speed, we have to note that the network environment of stability and security, such as service providers whether or not to use a Cisco, 3Com router to connect to the network, whether or not to buy a gateway firewall, whether the person has the entire days, 24 hours surveillance of the various attacks from the network ... ... only with the above-mentioned conditions is the hosting service provider we have chosen to target.
Some virtual hosting service providers to find any article of low-bandwidth lines, and then a patchwork of some equipment, know how to debug to find the two Windows 2000 technical personnel, and then hurried on to provide services. Even if its cheaper price, we do not recommended.
Stability services from service provider infrastructure. Configuration than the high-end servers, with redundant equipment, RAID cards, etc.; have to guarantee a stable power input UPS, emergency generators; have to maintain constant temperature and humidity of the equipment and so on. Of course, these hardware facilities, and sometimes it is impossible for us personally to see. Therefore, prior to purchase through various channels (such as the service provider's Web site) to learn more about how service providers is very important! After all, the enemy in order to find a suitable host!
■ how much space you need
Virtual host server to provide the type of hard disk space is divided into independent Web space, database space, office space, such as an independent. Virtual hosting space the size of the main basis of the number of published information. If your site contains about 10-150 pages, page count related pictures, has more than 100 KB, then you 60MB of space leased on the same subject. If the page more than a few hundred pages, and the need for database support, then you need the corresponding space should be between 100MB to 200MB. The actual space required may be an important qualification to apply for the service price increase in size; if one started to buy a lot of space to the total also do not have access to so many, can not retreat back also is a waste of money.
■ Virtual Host software requirements
Virtual host servers generally use Windows 2000 (NT) and UNIX (linux) two types of server operating systems, both have their own strong points. Database space is also divided into two categories: Windows 2000 platform, IIS 5.0/Access database space and Linux platforms MySQL / PHP database space. However I tend to select individuals or Unix (linux), however, often call for a variety of database and ASP web design needs of corporate users, it is only used Windows 2000 platforms, UNIX systems support the PHP.
■ Location and price
Server storage location is also a must buy when considered carefully. If the scope of the website information campaign abroad, and that the rental of the virtual server in the United States is the best option, because the United States the largest network bandwidth; if the scope of publicity, mainly in the domestic, then hire on the domestic telecommunications node server for the best. For prices, we are all very sensitive. Some telecommunications service provider's price is relatively high, but now many virtual hosts as the rise of service providers, virtual console prices now much lower.
■ after-sales service
Such as "Can not create e-mail," "Home can not be accessed" and so common after-sale problems, is probably a lot of friends have a virtual host often encountered. Some service providers will sell in the first place, after-sales service is not very perfect, if only in the Home Setting Method to do a mail, FTP setting methods, and technical issues, "e-mail" link on the done. The Hotline is advertised local telephone service provider, if a friend encountered field problems have their own long-distance foot the bill. With local after-sales service support, the national free phone support 800 after the company, no doubt, let us rest assured that before purchasing a lot. Before the purchase can be loaded into a customer asked about some problems, service providers pay attention to after-sales service quality and attitude, excellent after-sales service in the future use of the virtual host will be a lot easier.
http://www.cdddd.cn