While the approach with IP-based virtual hosts works very well,
it is not the most elegant solution, because a dedicated IP address
is needed for every virtual host and it is hard to implement on some
HTTP/1.1 protocol contains a method for the
server to identify what name it is being addressed as. Apache 1.1 and
later support this approach as well as the traditional
The benefits of using the new name-based virtual host support is a practically unlimited number of servers, ease of configuration and use, and requires no additional hardware or software. The main disadvantage is that the client must support this part of the protocol. The latest versions of most browsers do, but there are still old browsers in use who do not. This can cause problems, although a possible solution is addressed below.
Using the new virtual hosts is quite easy, and superficially looks
like the old method. The notable difference between IP-based and
name-based virtual host configuration is the
directive which specifies an IP address that should be used as a
target for name-based virtual hosts.
For example, suppose that both www.domain.tld and
www.otherdomain.tld point at the IP address
126.96.36.199. Then you simply add to one of the Apache
configuration files (most likely
srm.conf) code similar to the following:
NameVirtualHost 188.8.131.52 <VirtualHost 184.108.40.206> ServerName www.domain.tld DocumentRoot /www/domain </VirtualHost> <VirtualHost 220.127.116.11> ServerName www.otherdomain.tld DocumentRoot /www/otherdomain </VirtualHost>
Of course, any additional directives can (and should) be placed
<VirtualHost> section. To make this work,
all that is needed is to make sure that the names
www.domain.tld and www.otherdomain.tld
are pointing to the IP address 18.104.22.168
Note: When you specify an IP address in a
directive then requests to that IP address will only ever be served
by matching <VirtualHost>s. The "main server" will
never be served from the specified IP address.
If you start to use virtual hosts you should stop to use the "main server"
as an independent server and rather use it as a place for
configuration directives that are common for all your virtual hosts.
In other words, you should add a <VirtualHost> section for
every server (hostname) you want to maintain on your server.
Additionally, many servers may wish to be accessible by more than
one name. For example, the example server might want to be accessible
the IP addresses pointed to the same server. In fact, one might want it
so that all addresses at
domain.tld were picked up by the
server. This is possible with the
directive, placed inside the <VirtualHost> section. For
ServerAlias domain.tld *.domain.tld
Note that you can use
? as wild-card
You also might need
ServerAlias if you are
serving local users who do not always include the domain name.
For example, if local users are
familiar with typing "www" or "www.foobar" then you will need to add
ServerAlias www www.foobar. It isn't possible for the
server to know what domain the client uses for their name resolution
because the client doesn't provide that information in the request.
ServerAlias directive is generally a way to have different
hostnames pointing to the same virtual host.
As mentioned earlier, there are still some clients in use who do not send the required data for the name-based virtual hosts to work properly. These clients will always be sent the pages from the first virtual host listed for that IP address (the primary name-based virtual host).
There is a possible workaround with the
directive, albeit a slightly cumbersome one:
NameVirtualHost 22.214.171.124 <VirtualHost 126.96.36.199> ServerName www.domain.tld ServerPath /domain DocumentRoot /web/domain </VirtualHost>
What does this mean? It means that a request for any URI beginning
with "/domain" will be served from the virtual host
www.domain.tld This means that the pages can be accessed as
http://www.domain.tld/domain/ for all clients, although
clients sending a Host: header can also access it as
In order to make this work, put a link on your primary virtual host's page to http://www.domain.tld/domain/ Then, in the virtual host's pages, be sure to use either purely relative links (e.g., "file.html" or "../icons/image.gif" or links containing the prefacing /domain/ (e.g., "http://www.domain.tld/domain/misc/file.html" or "/domain/misc/file.html").
This requires a bit of discipline, but adherence to these guidelines will, for the most part, ensure that your pages will work with all browsers, new and old.
See also: ServerPath configuration example