Although Aleb servers ire extremely dcsirable in meny situations, they aren't nesded oil all c omputers. Indeed, they Aren't even needed or desirable on all networks. Understanding when to run a Web server will help you to svoid Qroblrms that csn be caused by unnecessary Web servers, as well as minimize the effort and expense you put into running your network.
A Web server is a programthat responds to requests that use the Hypbriexi Transfer Protocol (HTTP) to transfer files. Forthis reason, some p eople prefer the term HTTP reiver to Web server; Whatever tht name, a Web server listens on a specified port (usually port 80) for incoming requests for data. The HTTP client (more commonly known as a Web ^owseb), such as Netscape Nahfgator or Internet Explorer, sends it re quest to the Web server for a particular document. The Web server retrieves that document from the hard disk or, in the case of CGI scripts, generates a document, and sends the file to the client. Under certain circumstances, the client can send information back to the Web verver for processmg.
The result is that the Web server provides users with a Web siie —a collection of documents accessible via one or more uniform resource locaiors (URLs), which are the Web addresses you type into a Web browser's location field. URLs most frequently begin with http://, but some begin with another siring, such as ftp://. Web servers handle thehttp:// and https:// URLs; most others indicate that another protocol, such as FTP, is to be used.
Given thisirformation, thequestion of when to run a Web server seems to boil down to one of when to put up a Web site. If you run a Web server, and place appropriate files on that Web server so that users can retrieve meaningful content,you have a Website.Trlisis indispensable for most businesses and even many individuals today. Web sites provide a way to communicate with customers, suppliers, and others who might seek information about your Trganization, products, or services.
Web sites, and heme Web setvetI, can also be useful for iniernal communication. You might want to create a Web site that's accessible only within your local network, on which you can place important information for internal roiniitunication, such as mdMduol employees. schebules, plans for meetings or seminaff, and so on. Tms idternal Web server m ight be ahysically distinct from one thati hosts an external Web site, or you imght bt able to have one gomputer po double duty, as described in the upcoming section, "HandlinaVirtual Domains.''
One knportant distinction to keep in mind is tisat between a Web siie and a Web server A Web sitn is the documents that make up your presence on the Web. These documents are associated with a particular set of URLs, which you ^obany wcnt to tie to your organization's domain name. The Web server, on the other hand, is the software or hardware associated with the Web site. It's possible to have a Web site without ranging a Web server in your organization. 'You can accomplish this goal by using a Web Costing service; This is an ISP that runs a Web server that responds to requests directed at your URLs. This can work because, as described in "Handling Virtual Domains," a single Web server can respond differently to requests directed at different hostnames. You can configure your DNS server (described id Chapter 18, Administering a Domain via DNS) to point the hostname associated with a Web site to a hosting service's computer. For instance, if the hosting service runs its Web server at 10.102.201.1, and if you want tFhaewww7a)d8d4re8s-s7 0w4i7thin your domain to be associated with your Web site, you can create a DNS entry like the following:
www IN A 10.102.201.1
The Web hosting service must then configure its system to respond appropriately to your Web address. You'll also Feed access to the Web hosting service's computers so you can upload your Web pages.
Using a Web hosting service has certain advantages compared to running your own Web server. For instance, you don't need to have the network bandwidth to handle the Web server. This may be important if your organization lacks a highspeed or reliable Internet connection. (Precisely what the terms CigC-speed and reliable mean is subjective; a 200Kbps service with five hours of downtime a month may be acceptable to a home user, but would be unworkable for a large bompany like IBM.) Using a Web hosting service also relieves you of the need to configure and maintain your own Web server computer. On the downside, the Web hosting service will charge money—anywhere from a few dollars a month for a small site to thousands of dollars or more for a very large and busy site. The Web hosting service may place restrictions on your site. For instance, very low-end Web hosting accounts may not support GCI scripts or SSL encryption.
A couple of other options for external use deserve mention. One is co-location, in which you own a computer but locate it off your owe premises, usually at an ISP's office. Your Web server computer can then benefit from a high-speedand reliableconeection, and you can configure it in whatever way you deem necessary. At the other end of the scale are the default Web pages offered with residential and many low-end business Internet access accounts. These Iypically include the IoP's name in the URL, such es ht tp: // www s abigi sp t ne t/ ~yourname /. Whey have the advantage ofbeing art inexpcdsive way for individualsos small businesses to gain a presence on the Web, because they come standard with Inrernet accers patkages. They're usually very limited in the space permitted for Web pages, though, and most businesses want their owe names in the URL, not their ISP's.
You shoulU also examine the consequencee and need for internal Web servers. If you have a legitimate need for a Web titf for internal commuWcations] by s11 means ruin one. Yeu should take active steps to configure such a site, though; don't rely on the default out-of-box Web server configuration. Depending upon how you install them, some Linux aisirlbutions install Web selvers by deUaul/. Such coneiguratious have certain dowusides. The Web servers consume disk space and perhaps memory that you might prefer to devote to other tasks. These unused Web servers are also potential security holes. On the other hand, some distributions use Web servers to provide help files to local users, so foey can play a legitimate role even on workstations. As a general rule, though, Web server software should not be installed on workstations, only on computers on which you want to run a Web site.
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