Best way to make www.example.com AND example.com use the same session variables?

Question

I'm working on a webpage (let's call it example.com) and added the DNS record under CNAME (Alias):

Host Record Points    to  TTL
www  example.com       14400

However when I navigate through example.com, the session variables that are set are not retained if I go to www.example.com

What is the best way to make www.example.com AND example.com use the same session variables?

I'm using ubuntu 12.04, php5, apache2.

<VirtualHost *:80>
    ServerAdmin webmaster@localhost
    ServerName www.example.com
    Redirect 301 / http://example.com/
    DocumentRoot /var/www/public_html
    <Directory />
            Options FollowSymLinks
            AllowOverride None
    </Directory>
    <Directory /var/www/public_html>
            Options Indexes FollowSymLinks MultiViews
            AllowOverride None
            Order allow,deny
            allow from all
    </Directory>

    ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
    <Directory "/usr/lib/cgi-bin">
            AllowOverride None
            Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
            Order allow,deny
            Allow from all
    </Directory>

    ErrorLog /var/log/apache2/error.log

    # Possible values include: debug, info, notice, warn, error, crit,
    # alert, emerg.
    LogLevel warn

    CustomLog /var/log/apache2/access.log combined

Alias /doc/ "/usr/share/doc/"
<Directory "/usr/share/doc/">
    Options Indexes MultiViews FollowSymLinks
    AllowOverride None
    Order deny,allow
    Deny from all
    Allow from 127.0.0.0/255.0.0.0 ::1/128
</Directory>

Answer 1

What is the best way to make www.mysite.com AND mysite.com use the same session variables?

The best way is to not have both host names running the same site.

Pick one of them to be canonical, then redirect everything from the other to the canonical one.

<VirtualHost *:80>
ServerName example.com
Redirect 301 / http://www.example.com
etc

Answer 2

你应该去的最好的方法是将mysite.com重定向到www.mysite.com ，反之亦然 - 只为域别名提供一个站点（一个内容）...