www.Example.com works but not root (Example.com)

Question

I am using Apache2 with UBUNTU14 LTS, all "standard" server.

The problem is simple, when using http://www.example.com it works fine, but when using http://example.com it doesn't, it goes to the wrong index.

---

Describing details

I have folders at ls /var/www/

  example.com  example2.example  html              
  wiki.example.com  wp.example2.example              

Each with different and good index.htm working with http://www.example.com (goes to /var/www/example.com) or http://wiki.example.com, etc. But the index of http://example.com goes to /var/www/html/index.htm, not to /var/www/example.com (!).

---

At /etc/apache2/sites-available/example.com.conf we have,

<VirtualHost *:80>
    ServerAdmin [email protected]
        ServerName example.com
        ServerAlias www.example.com
    DocumentRoot /var/www/example.com

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

</VirtualHost>


<VirtualHost *:80>
    ServerName wiki.example.com
    DocumentRoot /var/www/wiki.example.com
</VirtualHost>

---

EDIT (notes)

We are using a workaround — and please ignore the "real world" examples in the comments, it is not valid as real testing —, an ugly piece of PHP code (not a solution) in the /var/www/html/index.php of the root (no subdomain), to redirect to www subdomain,

  if ( preg_match(  // if HTTP from other domain, redirects 
         '/(mydomain1|mydomain2|mydomain3)/',
         strtolower($_SERVER['HTTP_HOST']),
         $m
      ) ) switch($m[1]) {
    case 'mydomain1':
        header("Location: https://www.example.com"); die('');
    case 'mydomain2':
        header("Location: https://www.example2.example"); die('');
    case '...':
        header("Location: https://www...."); die('');
    }

---

EDIT

As @covener comment suggest, apachectl -S, results in

VirtualHost configuration:
*:80                   is a NameVirtualHost
         default server localhost (/etc/apache2/sites-enabled/000-default.conf:1)
         port 80 namevhost localhost (/etc/apache2/sites-enabled/000-default.conf:1)
         port 80 namevhost atarica.com.br (/etc/apache2/sites-enabled/atarica.com.br.conf:1)
                 alias www.atarica.com.br
         port 80 namevhost wiki.atarica.com.br (/etc/apache2/sites-enabled/atarica.com.br.conf:13)
         port 80 namevhost atarica.com.br (/etc/apache2/sites-enabled/fabrincantes.com.conf:1)
                 alias www.fabrincantes.com
         port 80 namevhost yellowtown.org (/etc/apache2/sites-enabled/yellowtown.org.conf:1)
                 alias www.yellowtown.org
         port 80 namevhost wiki.yellowtown.org (/etc/apache2/sites-enabled/yellowtown.org.conf:35)
ServerRoot: "/etc/apache2"
Main DocumentRoot: "/var/www"
Main ErrorLog: "/var/log/apache2/error.log"
Mutex default: dir="/var/lock/apache2" mechanism=fcntl 
Mutex mpm-accept: using_defaults
Mutex watchdog-callback: using_defaults
PidFile: "/var/run/apache2/apache2.pid"
Define: DUMP_VHOSTS
Define: DUMP_RUN_CFG
User: name="www-data" id=33 not_used
Group: name="www-data" id=33 not_used

Answer 1

Try this:

<VirtualHost *:80>
    ServerName example.com
    Redirect permanent / http://www.example.com/
</VirtualHost>

Then you just need to create another section with ServerName www.example.com for your real server configuration.

Also, wouldn't CNAME's records work has an alternative to this? (I'm not sure)