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From cove...@apache.org
Subject svn commit: r1043516 - /httpd/httpd/trunk/docs/manual/vhosts/name-based.xml
Date Wed, 08 Dec 2010 16:52:34 GMT
Author: covener
Date: Wed Dec  8 16:52:34 2010
New Revision: 1043516

URL: http://svn.apache.org/viewvc?rev=1043516&view=rev
Log:
Move the description of how a name-based vhost is picked to the top
instead of burying it.  Reword some other "default vhost" references.


Modified:
    httpd/httpd/trunk/docs/manual/vhosts/name-based.xml

Modified: httpd/httpd/trunk/docs/manual/vhosts/name-based.xml
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/vhosts/name-based.xml?rev=1043516&r1=1043515&r2=1043516&view=diff
==============================================================================
--- httpd/httpd/trunk/docs/manual/vhosts/name-based.xml (original)
+++ httpd/httpd/trunk/docs/manual/vhosts/name-based.xml Wed Dec  8 16:52:34 2010
@@ -39,10 +39,9 @@
     determine the correct virtual host to serve.  Therefore you need to
     have a separate IP address for each host.</p>
 
-    <p>With name-based virtual
-    hosting, the server relies on the client to report the hostname as
-    part of the HTTP headers.  Using this technique, many different hosts
-    can share the same IP address.</p>
+    <p>With name-based virtual hosting, the server relies on the client to 
+    report the hostname as part of the HTTP headers.  Using this technique, 
+    many different hosts can share the same IP address.</p>
 
     <p>Name-based virtual hosting is usually simpler, since you need
     only configure your DNS server to map each hostname to the correct
@@ -63,6 +62,30 @@
         they are on separate IP addresses.</li>
     </ul>
 
+
+</section>
+
+<section id="alg"><title>How the server selects the proper name-based virtual
host</title>
+
+    <p>It is important to recognize that the first step in name-based virtual
+    host resolution is IP-based resolution.  Name-based virtual host
+    resolution only chooses the most appropriate name-based virtual host
+    after narrowing down the candidates to the best IP-based match.  Using a wildcard (*)
+    for the IP address in all of the NameVirtualHost and VirtualHost directives makes this
+    IP-based mapping irrelevant.</p>
+    
+    <p>When a request arrives, the server will first check if it is using
+    an IP address that matches exactly any <directive module="core"
+    >NameVirtualHost</directive>. If it is, then it will look at each <directive
+    type="section" module="core">VirtualHost</directive> section with a (literal)
matching
+    IP address and try to find one where the <directive module="core"
+    >ServerName</directive> or <code>ServerAlias</code> matches the
requested
+    hostname. If it finds one, then it uses the configuration for that server.</p>
+
+    <p id="defaultvhost"> If no matching ServerName or ServerAlias is found in the
+    set of virtual hosts matching the NameVirtualHost directive, then 
+    <strong>the first listed virtual host</strong> that matches the IP 
+    address will be used.</p>
 </section>
 
 <section id="using"><title>Using Name-based Virtual Hosts</title>
@@ -113,20 +136,23 @@
     lives.</p>
 
     <note><title>Main host goes away</title>
-        <p>If you are adding virtual hosts to an existing web server, you
-        must also create a <directive type="section" module="core"
-        >VirtualHost</directive> block for the existing host. The <directive
-        module="core">ServerName</directive> and <directive module="core"
-        >DocumentRoot</directive> included in this virtual host should be the
-        same as the global <directive module="core">ServerName</directive> and
-        <directive module="core">DocumentRoot</directive>. List this virtual
-        host first in the configuration file so that it will act as the default
-        host.</p>
+        <p> Any request that doesn't match an existing <directive type="section"
+        module="core">VirtualHost</directive> is handled by the global
+        server configuration, regardless of the hostname or ServerName.</p>
+
+        <p> When you add a name-based virtual host to an existing server, and 
+        the virtual host arguments match preexisting IP and port combinations, 
+        requests will now be handled by an explicit virtual host.  In this case,
+        it's usually wise to create a <a href="#defaultvhost">default virtual host</a>
+        with a <directive module="core">ServerName</directive> matching that
of 
+        the base server.  New domains on the same interface and port, but
+        requiring separate configurations,  can then be added as subsequent (non-default)
+        virtual hosts.</p>
     </note>
 
     <p>For example, suppose that you are serving the domain
-    <code>www.domain.tld</code> and you wish to add the virtual host
-    <code>www.otherdomain.tld</code>, which points at the same IP address.
+    <code>www.example.com</code> and you wish to add the virtual host
+    <code>other.example.com</code>, which points at the same IP address.
     Then you simply add the following to <code>httpd.conf</code>:</p>
 
     <example>
@@ -134,14 +160,15 @@
         <br />
         &lt;VirtualHost *:80&gt;<br />
         <indent>
-            ServerName www.domain.tld<br />
-            ServerAlias domain.tld *.domain.tld<br />
+            # This first-listed virtual host is also the default for *:80
+            ServerName www.example.com<br />
+            ServerAlias example.com *.example.com<br />
             DocumentRoot /www/domain<br />
         </indent>
         &lt;/VirtualHost&gt;<br />
         <br />
         &lt;VirtualHost *:80&gt;<br />
-        <indent>ServerName www.otherdomain.tld<br />
+        <indent>ServerName other.example.com<br />
             DocumentRoot /www/otherdomain<br />
         </indent>
         &lt;/VirtualHost&gt;<br />
@@ -164,11 +191,11 @@
     web site:</p>
 
     <example>
-        ServerAlias domain.tld *.domain.tld
+        ServerAlias example.com *.example.com
     </example>
 
-    <p>then requests for all hosts in the <code>domain.tld</code> domain
will
-    be served by the <code>www.domain.tld</code> virtual host. The wildcard
+    <p>then requests for all hosts in the <code>example.com</code> domain
will
+    be served by the <code>www.example.com</code> virtual host. The wildcard
     characters <code>*</code> and <code>?</code> can be used to match
names.
     Of course, you can't just make up names and place them in <directive
     module="core">ServerName</directive> or <code>ServerAlias</code>.
You must
@@ -186,25 +213,6 @@
     container) will be used only if they are not overridden by the virtual host
     settings.</p>
 
-    <p>Now when a request arrives, the server will first check if it is using
-    an IP address that matches the <directive module="core"
-    >NameVirtualHost</directive>. If it is, then it will look at each <directive
-    type="section" module="core">VirtualHost</directive> section with a matching
-    IP address and try to find one where the <directive module="core"
-    >ServerName</directive> or <code>ServerAlias</code> matches the
requested
-    hostname. If it finds one, then it uses the configuration for that server.
-    If no matching virtual host  is found, then <strong>the first listed virtual
-    host</strong> that matches the IP address will be used.</p>
-
-    <p>As a consequence, the first listed virtual host is the <em>default</em>
-    virtual host.  The <directive module="core">DocumentRoot</directive> from
-    the <em>main server</em> will <strong>never</strong> be used
when an IP
-    address matches the <directive module="core">NameVirtualHost</directive>

-    directive. If you would like to have a special configuration for requests 
-    that do not match any particular virtual host, simply put that configuration
-    in a <directive type="section" module="core">VirtualHost</directive>
-    container and list it first in the configuration file.</p>
-
 </section>
 
 </manualpage>



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