Drupal have session-handling settings in the following three cases:

1. In .htaccess file
2. In settings.php file,
3. In bootstrap code in the includes/bootstrap.inc file.

In .htaccess
Drupal has full control when sessions start by turning off PHP’s session.auto_start functionality in the Drupal installation’s default .htaccess file with the
following line:

php_value session.auto_start 0

session.auto_start is a configuration option that PHP cannot change at runtime, which is why it lives here instead of settings.php.

In settings.php

Each of the default tpl.php files represents an override to a themable function from the Drupal core.

theme_page, theme_node, theme_comment, theme_box, and theme_block are the common themable functions, and so have direct impact on the appearance of your site, but they are not the only functions available for modification. Core Drupal includes lot more themable functions.

However, finding themable functions, at the most basic level, is easy. You just need to search for function theme_. Everything that turns up is a themable function and can be overridden.

Drupal is an open source popular and powerful content management system. The most important features of Drupal is that it allows you host multisites from a single installed Drupal code base i.e it can serve multiple web sites, each with its own individual configuration.

Here, I will show you how to setup multisite from single drupal code base.

First we need to install one Drupal instance as per the instruction in the installation guide from Drupal official site. Here, I will show you how to add another domain to one Drupal installation.