The hosting service must include system administration since it is shared by many users; this is a benefit for users that do not want to deal with it, but a hindrance to power users that want more control.
Shared hosting typically uses a web-based control panel system, such as cPanel, Plesk, Helm, H-Sphere, Ensim, Sphera or one of many other control panel products.
In shared hosting, the provider is generally responsible for management of servers, installation of server software, security updates and other aspects of the service. Servers are often based on the Linux operating systems because more Control Panel products (see above) are made for Linux. However, some providers offer Microsoft Windows based solutions. The Plesk control panel, for instance, has two versions - for Linux and Windows, both with very similar interfaces and functionality, with the exception of OS-specific differences (for example, supporting ASP.NET, or Microsoft SQL Server on Windows).
There are thousands of shared hosting providers in the United States alone. They range from mom-and-pop shops, to small design firms, to multi-million dollar providers with hundreds of thousands of customers. A large portion of the shared web hosting market is driven through Pay Per Click advertising (PPC) or Affiliate programs.
Shared web hosting can also be done privately by sharing the cost of running a server in a colocation centre; this is called cooperative hosting.
Implementation
Shared web hosting can be accomplished in two ways: name-based and IP-based.
Name-based
In name-based virtual hosting, also called shared IP hosting, the virtual hosts serve multiple hostnames on a single machine with a single IP address.
When a web browser requests a resource from a web server using HTTP/1.1 it includes the requested hostname as part of the request. The server uses this information to determine which web site to show the user.
IP-based
In IP-based virtual hosting, also called dedicated IP hosting, each virtual host has a different IP address. The web server is configured with multiple physical network interfaces, or virtual network interfaces on the same physical interface. The web server software uses the IP address the client connects to in order to determine which web site to show the user.
Cons
Name-based virtual hosts have some disadvantages:
They will not work with browsers that do not send the hostname as part of requests. This is true for older HTTP/1.0 browsers that has not retrofitted the host field feature from the HTTP/1.1 protocol.
They do not support secure websites (HTTPS). All name-based virtual hosts using the same IP address must share the same digital certificate. This is because the SSL/TLS handshake takes place before the hostname is sent to the server. Thus the server doesn't know which encryption key to use when the connection is made. An extension to the TLS protocol, part of RFC 3546 - Transport Layer Security (TLS) Extensions, specifies a way for the client to provide the requested host name as part of the handshake, but it is not yet widely implemented.
If the Domain Name System is malfunctioning, it is harder to use a name-based virtually-hosted website. Ordinarily, in this case, the user could fall back to using the IP address to contact the system, as in http://12.34.56.78/. However, the web browser doesn't know what hostname to send to the server, but a name-based virtual host requires it. |
