Apache Guide: Setting Up Virtual Hosts Page 3

Of course, sometimes, you don't have the luxury of giving your machine multiple IP addresses. IP addresses are in shorter and shorter supply, and frequently, such as if you have an DSL connection as I do, you only have one. In this case, name-based virtual hosting is for you.

You don't have to give your machine multiple IP addresses, but you will still have to contact the person that is responsible for your DNS server, and have them put more than one DNS record in for your machine. These extra records are called C-records, or CNames. (The main record pointing at a machine is called the AName, or A-record.) You can have as many CNames as you like pointing to a particular machine.

Once you have your DNS configured to send traffic to you for all these names, you'll need to do the following in your server configuration file:

        ServerName name1.mydomain.com
        DocumentRoot /usr/local/apache/name1docs
        ServerAlias name1
        ServerName name2.mydomain.com
        DocumentRoot /usr/local/apache/name2docs
        ServerAlias name2
        ServerName name3.mydomain.com
        DocumentRoot /usr/local/apache/name3docs
        ServerAlias name3

Once again, as in the IP-based virtual hosts, you can put any directive you want in these sections. I've kept them all pretty simple.

There are several things to note here.

First, you must specify, with the NameVirtualHost directive, what IP address should be responding to virtual host requests. You can use IP-based and name-based virtual hosting in conjunction - that is, you can do both on the same server at the same time. So you must specify which addresses you're using for this. I'll frequently set up virtual hosts on the internal and external interface of a server (intranet servers and internet servers, that is) and so you must specify both addresses:


Furthermore, you can run virtual hosts on different ports, as well as different addresses, if you really want to complicate things:


Just make sure that all the names make it into DNS, or you might end up serving a page that you were not intending to.

The magic for the virtual host stuff is that the browser tells the server what server it is requesting content from. There are still some older browsers in use that don't do this correctly, and so they might get content from the "default" server on your machine. This is almost never a real consideration, since any browser produced in the last five years (perhaps even before that--I tend to lose track of time these days) has this ability. There are work-arounds in Apache so that it will work for even these browsers, but I'll let you research that on your own, if you really want to. Start at http://www.apache.org/docs/manual/vhosts/index.html and go from there.

Running Multiple Daemons

There's actually a third alternative. You can run completely separate server daemons on your server machine and have each one serving a separate Web site. The downside of this is that each one must run on a different port, since you can't have multiple services listening on the same port at the same time.

You can get a server to run with a particular configuration file with the -f command-line option:

This article was originally published on Jul 17, 2000
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