diff --git a/wp-admin/includes/ms.php b/wp-admin/includes/ms.php
index 58778ec7b8..1646309e9f 100644
--- a/wp-admin/includes/ms.php
+++ b/wp-admin/includes/ms.php
@@ -732,7 +732,7 @@ function site_admin_notice() {
 add_action( 'admin_notices', 'site_admin_notice' );
 
 function avoid_blog_page_permalink_collision( $data, $postarr ) {
-	if( constant( 'VHOST' ) == 'yes' )
+	if( is_subdomain_install() )
 		return $data;
 	if( $data[ 'post_type' ] != 'page' )
 		return $data;
diff --git a/wp-admin/ms-edit.php b/wp-admin/ms-edit.php
index c26f6ca6a7..22ba6a85d0 100644
--- a/wp-admin/ms-edit.php
+++ b/wp-admin/ms-edit.php
@@ -70,7 +70,7 @@ switch( $_GET['action'] ) {
 			if ( false === $blog_details ) {
 				if ( is_numeric( $dashboard_blog ) )
 					wp_die( __( 'Dashboard blog_id must be a blog that already exists' ) );
-				if ( constant( 'VHOST' ) == 'yes' ) {
+				if ( is_subdomain_install() ) {
 					$domain = $dashboard_blog . '.' . $current_site->domain;
 					$path = $current_site->path;
 				} else {
@@ -145,7 +145,7 @@ switch( $_GET['action'] ) {
 		if( !is_email( $email ) )
 			wp_die( __('Invalid email address') );
 
-		if( constant( 'VHOST' ) == 'yes' ) {
+		if( is_subdomain_install() ) {
 			$newdomain = $domain.".".$current_site->domain;
 			$path = $base;
 		} else {
diff --git a/wp-admin/ms-options.php b/wp-admin/ms-options.php
index 46c622de90..6f641034f2 100644
--- a/wp-admin/ms-options.php
+++ b/wp-admin/ms-options.php
@@ -55,7 +55,7 @@ if (isset($_GET['updated'])) {
 					<label><input name="registration" type="radio" id="registration3" value='user' <?php echo get_site_option('registration') == 'user' ? 'checked="checked"' : ''; ?> /> <?php _e('Only user account can be created.'); ?></label><br />
 					<label><input name="registration" type="radio" id="registration4" value='blog' <?php echo get_site_option('registration') == 'blog' ? 'checked="checked"' : ''; ?> /> <?php _e('Only logged in users can create new blogs.'); ?></label><br />
 					<p><?php _e('Disable or enable registration and who or what can be registered. (Default=all)'); ?></p>
-					<?php if( constant( 'VHOST' ) == 'yes' ) {
+					<?php if( is_subdomain_install() ) {
 						echo "<p>" . __('If registration is disabled, please set "NOBLOGREDIRECT" in wp-config.php to a url you will redirect visitors to if they visit a non existant blog.') . "</p>";
 					} ?>
 				</td>
diff --git a/wp-admin/ms-sites.php b/wp-admin/ms-sites.php
index 41fe86c83a..4bb24a0c6f 100644
--- a/wp-admin/ms-sites.php
+++ b/wp-admin/ms-sites.php
@@ -401,7 +401,7 @@ switch( $_GET['action'] ) {
 
 		<?php
 		// define the columns to display, the syntax is 'internal name' => 'display name'
-		$blogname_columns = ( constant( "VHOST" ) == 'yes' ) ? __('Domain') : __('Path');
+		$blogname_columns = ( is_subdomain_install() ) ? __('Domain') : __('Path');
 		$posts_columns = array(
 			'id'           => __('ID'),
 			'blogname'     => $blogname_columns,
@@ -457,7 +457,7 @@ switch( $_GET['action'] ) {
 					}
 					echo "<tr $bgcolour class='$class'>";
 
-					$blogname = ( constant( "VHOST" ) == 'yes' ) ? str_replace('.'.$current_site->domain, '', $blog['domain']) : $blog['path'];
+					$blogname = ( is_subdomain_install() ) ? str_replace('.'.$current_site->domain, '', $blog['domain']) : $blog['path'];
 					foreach( $posts_columns as $column_name=>$column_display_name ) {
 						switch($column_name) {
 							case 'id': ?>
@@ -586,7 +586,7 @@ switch( $_GET['action'] ) {
 					<tr class="form-field form-required">
 						<th style="text-align:center;" scope='row'><?php _e('Blog Address') ?></th>
 						<td>
-						<?php if ( constant( "VHOST" ) == 'yes' ) { ?>
+						<?php if ( is_subdomain_install() ) { ?>
 							<input name="blog[domain]" type="text" title="<?php _e('Domain') ?>"/>.<?php echo $current_site->domain;?>
 						<?php } else {
 							echo $current_site->domain . $current_site->path ?><input name="blog[domain]" type="text" title="<?php _e('Domain') ?>"/>
diff --git a/wp-config-sample.php b/wp-config-sample.php
index c884ff0cd7..19cc8ab456 100644
--- a/wp-config-sample.php
+++ b/wp-config-sample.php
@@ -1,76 +1,76 @@
-<?php
-/** 
- * The base configurations of the WordPress.
- *
- * This file has the following configurations: MySQL settings, Table Prefix,
- * Secret Keys, WordPress Language, and ABSPATH. You can find more information by
- * visiting {@link http://codex.wordpress.org/Editing_wp-config.php Editing
- * wp-config.php} Codex page. You can get the MySQL settings from your web host.
- *
- * This file is used by the wp-config.php creation script during the
- * installation. You don't have to use the web site, you can just copy this file
- * to "wp-config.php" and fill in the values.
- *
- * @package WordPress
- */
-
-// ** MySQL settings - You can get this info from your web host ** //
-/** The name of the database for WordPress */
-define('DB_NAME', 'putyourdbnamehere');
-
-/** MySQL database username */
-define('DB_USER', 'usernamehere');
-
-/** MySQL database password */
-define('DB_PASSWORD', 'yourpasswordhere');
-
-/** MySQL hostname */
-define('DB_HOST', 'localhost');
-
-/** Database Charset to use in creating database tables. */
-define('DB_CHARSET', 'utf8');
-
-/** The Database Collate type. Don't change this if in doubt. */
-define('DB_COLLATE', '');
-
-/**#@+
- * Authentication Unique Keys.
- *
- * Change these to different unique phrases!
- * You can generate these using the {@link https://api.wordpress.org/secret-key/1.1/ WordPress.org secret-key service}
- * You can change these at any point in time to invalidate all existing cookies. This will force all users to have to log in again.
- *
- * @since 2.6.0
- */
-define('AUTH_KEY', 'put your unique phrase here');
-define('SECURE_AUTH_KEY', 'put your unique phrase here');
-define('LOGGED_IN_KEY', 'put your unique phrase here');
-define('NONCE_KEY', 'put your unique phrase here');
-/**#@-*/
-
-/**
- * WordPress Database Table prefix.
- *
- * You can have multiple installations in one database if you give each a unique
- * prefix. Only numbers, letters, and underscores please!
- */
-$table_prefix  = 'wp_';
-
-/**
- * WordPress Localized Language, defaults to English.
- *
- * Change this to localize WordPress.  A corresponding MO file for the chosen
- * language must be installed to wp-content/languages. For example, install
- * de.mo to wp-content/languages and set WPLANG to 'de' to enable German
- * language support.
- */
-define ('WPLANG', '');
-
-/* That's all, stop editing! Happy blogging. */
-
-/** Absolute path to the WordPress directory. */
-if ( !defined('ABSPATH') )
-	define('ABSPATH', dirname(__FILE__) . '/');
-
-/** Sets up WordPress vars and included files. */
-require_once(ABSPATH . 'wp-settings.php');
+<?php
+/** 
+ * The base configurations of the WordPress.
+ *
+ * This file has the following configurations: MySQL settings, Table Prefix,
+ * Secret Keys, WordPress Language, and ABSPATH. You can find more information by
+ * visiting {@link http://codex.wordpress.org/Editing_wp-config.php Editing
+ * wp-config.php} Codex page. You can get the MySQL settings from your web host.
+ *
+ * This file is used by the wp-config.php creation script during the
+ * installation. You don't have to use the web site, you can just copy this file
+ * to "wp-config.php" and fill in the values.
+ *
+ * @package WordPress
+ */
+
+// ** MySQL settings - You can get this info from your web host ** //
+/** The name of the database for WordPress */
+define('DB_NAME', 'putyourdbnamehere');
+
+/** MySQL database username */
+define('DB_USER', 'usernamehere');
+
+/** MySQL database password */
+define('DB_PASSWORD', 'yourpasswordhere');
+
+/** MySQL hostname */
+define('DB_HOST', 'localhost');
+
+/** Database Charset to use in creating database tables. */
+define('DB_CHARSET', 'utf8');
+
+/** The Database Collate type. Don't change this if in doubt. */
+define('DB_COLLATE', '');
+
+/**#@+
+ * Authentication Unique Keys.
+ *
+ * Change these to different unique phrases!
+ * You can generate these using the {@link https://api.wordpress.org/secret-key/1.1/ WordPress.org secret-key service}
+ * You can change these at any point in time to invalidate all existing cookies. This will force all users to have to log in again.
+ *
+ * @since 2.6.0
+ */
+define('AUTH_KEY', 'put your unique phrase here');
+define('SECURE_AUTH_KEY', 'put your unique phrase here');
+define('LOGGED_IN_KEY', 'put your unique phrase here');
+define('NONCE_KEY', 'put your unique phrase here');
+/**#@-*/
+
+/**
+ * WordPress Database Table prefix.
+ *
+ * You can have multiple installations in one database if you give each a unique
+ * prefix. Only numbers, letters, and underscores please!
+ */
+$table_prefix  = 'wp_';
+
+/**
+ * WordPress Localized Language, defaults to English.
+ *
+ * Change this to localize WordPress.  A corresponding MO file for the chosen
+ * language must be installed to wp-content/languages. For example, install
+ * de.mo to wp-content/languages and set WPLANG to 'de' to enable German
+ * language support.
+ */
+define ('WPLANG', '');
+
+/* That's all, stop editing! Happy blogging. */
+
+/** Absolute path to the WordPress directory. */
+if ( !defined('ABSPATH') )
+	define('ABSPATH', dirname(__FILE__) . '/');
+
+/** Sets up WordPress vars and included files. */
+require_once(ABSPATH . 'wp-settings.php');
diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index bf5d2614aa..2ac7d8b7f5 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -31,7 +31,7 @@ function get_blogaddress_by_id( $blog_id ) {
 function get_blogaddress_by_name( $blogname ) {
 	global $current_site;
 
-	if( defined( "VHOST" ) && constant( "VHOST" ) == 'yes' ) {
+	if( is_subdomain_install() ) {
 		if( $blogname == 'main' )
 			$blogname = 'www';
 		return clean_url( "http://" . $blogname . "." . $current_site->domain . $current_site->path );
@@ -41,7 +41,7 @@ function get_blogaddress_by_name( $blogname ) {
 }
 
 function get_blogaddress_by_domain( $domain, $path ){
-	if( defined( "VHOST" ) && constant( "VHOST" ) == 'yes' ) {
+	if( is_subdomain_install() ) {
 		$url = "http://".$domain.$path;
 	} else {
 		if( $domain != $_SERVER['HTTP_HOST'] ) {
@@ -108,7 +108,7 @@ function get_id_from_blogname( $name ) {
 	if ( $blog_id )
 		return $blog_id;
 
-	if ( defined('VHOST') && constant( 'VHOST' ) == 'yes' ) {
+	if ( is_subdomain_install() ) {
 		$domain = $name . '.' . $current_site->domain;
 		$path = $current_site->path;
 	} else {
@@ -1033,7 +1033,7 @@ function wpmu_validate_blog_signup($blogname, $blog_title, $user = '') {
 		$errors->add('blogname', __("Sorry, blog names may not contain the character '_'!"));
 
 	// do not allow users to create a blog that conflicts with a page on the main blog.
-	if ( constant( "VHOST" ) == 'no' && $wpdb->get_var( $wpdb->prepare( "SELECT post_name FROM " . $wpdb->get_blog_prefix( $current_site->blog_id ) . "posts WHERE post_type = 'page' AND post_name = %s", $blogname ) ) ) {
+	if ( !is_subdomain_install() && $wpdb->get_var( $wpdb->prepare( "SELECT post_name FROM " . $wpdb->get_blog_prefix( $current_site->blog_id ) . "posts WHERE post_type = 'page' AND post_name = %s", $blogname ) ) ) {
 		$errors->add( 'blogname', __( "Sorry, you may not use that blog name" ) );
 	}
 
@@ -1051,7 +1051,7 @@ function wpmu_validate_blog_signup($blogname, $blog_title, $user = '') {
 	    $errors->add('blog_title', __("Please enter a blog title"));
 
 	// Check if the domain/path has been used already.
-	if( constant( "VHOST" ) == 'yes' ) {
+	if( is_subdomain_install() ) {
 		$mydomain = "$blogname.$domain";
 		$path = $base;
 	} else {
@@ -1138,7 +1138,7 @@ function wpmu_signup_blog_notification($domain, $path, $title, $user, $user_emai
 		return false;
 
 	// Send email with activation link.
-	if( constant( "VHOST" ) == 'no' || $current_site->id != 1 ) {
+	if( !is_subdomain_install() || $current_site->id != 1 ) {
 		$activate_url = "http://" . $current_site->domain . $current_site->path . "wp-activate.php?key=$key";
 	} else {
 		$activate_url = "http://{$domain}{$path}wp-activate.php?key=$key";
@@ -1267,7 +1267,7 @@ function wpmu_create_user( $user_name, $password, $email) {
 
 function wpmu_create_blog($domain, $path, $title, $user_id, $meta = '', $site_id = 1) {
 	$domain = preg_replace( "/\s+/", '', sanitize_user( $domain, true ) );
-	if( constant( 'VHOST' ) == 'yes' )
+	if( is_subdomain_install() )
 		$domain = str_replace( '@', '', $domain );
 	$title = strip_tags( $title );
 	$user_id = (int) $user_id;
diff --git a/wp-includes/ms-settings.php b/wp-includes/ms-settings.php
index 38bcd3eacc..a6a9e301b1 100644
--- a/wp-includes/ms-settings.php
+++ b/wp-includes/ms-settings.php
@@ -1,4 +1,19 @@
 <?php
+
+/**
+ * Whether a subdomain configuration is enabled
+ *
+ * @since 3.0
+ *
+ * @return bool True if subdomain configuration is enabled, false otherwise.
+ */
+function is_subdomain_install() {
+	if ( defined('VHOST') && VHOST == 'yes' )
+		return true;
+
+	return false;
+}
+
 if( isset( $current_site ) && isset( $current_blog ) )
 	return;
 
@@ -65,7 +80,7 @@ function wpmu_current_site() {
 		return $current_site;
 	}
 	$path = substr( $_SERVER[ 'REQUEST_URI' ], 0, 1 + strpos( $_SERVER[ 'REQUEST_URI' ], '/', 1 ) );
-	if( constant( 'VHOST' ) == 'yes' ) {
+	if( is_subdomain_install() ) {
 		$current_site = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->site WHERE domain = %s AND path = %s", $domain, $path) );
 		if( $current_site != null )
 			return $current_site;
@@ -113,7 +128,7 @@ $current_site = wpmu_current_site();
 if( !isset( $current_site->blog_id ) )
 	$current_site->blog_id = $wpdb->get_var( "SELECT blog_id FROM {$wpdb->blogs} WHERE domain='{$current_site->domain}' AND path='{$current_site->path}'" );
 
-if( constant( 'VHOST' ) == 'yes' ) {
+if( is_subdomain_install() ) {
 	$current_blog = wp_cache_get( 'current_blog_' . $domain, 'site-options' );
 	if( !$current_blog ) {
 		$current_blog = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->blogs WHERE domain = %s", $domain) );
@@ -143,7 +158,7 @@ if( constant( 'VHOST' ) == 'yes' ) {
 	}
 }
 
-if( defined( "WP_INSTALLING" ) == false && constant( 'VHOST' ) == 'yes' && !is_object( $current_blog ) ) {
+if( defined( "WP_INSTALLING" ) == false && is_subdomain_install() && !is_object( $current_blog ) ) {
 	if( defined( 'NOBLOGREDIRECT' ) ) {
 		$destination = constant( 'NOBLOGREDIRECT' );
 		if ( $destination == '%siteurl%' )
diff --git a/wp-signup.php b/wp-signup.php
index 71d7002425..2c6642a193 100755
--- a/wp-signup.php
+++ b/wp-signup.php
@@ -56,7 +56,7 @@ get_header();
 function show_blog_form($blogname = '', $blog_title = '', $errors = '') {
 	global $current_site;
 	// Blog name
-	if( constant( "VHOST" ) == 'no' )
+	if( !is_subdomain_install() )
 		echo '<label for="blogname">' . __('Blog Name:') . '</label>';
 	else
 		echo '<label for="blogname">' . __('Blog Domain:') . '</label>';
@@ -65,14 +65,14 @@ function show_blog_form($blogname = '', $blog_title = '', $errors = '') {
 		<p class="error"><?php echo $errmsg ?></p>
 	<?php }
 
-	if( constant( "VHOST" ) == 'no' ) {
+	if( !is_subdomain_install() ) {
 		echo '<span class="prefix_address">' . $current_site->domain . $current_site->path . '</span><input name="blogname" type="text" id="blogname" value="'. esc_attr($blogname) .'" maxlength="50" /><br />';
 	} else {
 		echo '<input name="blogname" type="text" id="blogname" value="'.esc_attr($blogname).'" maxlength="50" /><span class="suffix_address">.' . $current_site->domain . $current_site->path . '</span><br />';
 	}
 	if ( !is_user_logged_in() ) {
 		print '(<strong>' . __( 'Your address will be ' );
-		if( constant( "VHOST" ) == 'no' ) {
+		if( !is_subdomain_install() ) {
 			print $current_site->domain . $current_site->path . __( 'blogname' );
 		} else {
 			print __( 'domain.' ) . $current_site->domain . $current_site->path;
@@ -420,7 +420,7 @@ if( $active_signup == "none" ) {
 				_e( "You're logged in already. No need to register again!" );
 			}
 			if ($newblogname) {
-				if( constant( "VHOST" ) == 'no' )
+				if( !is_subdomain_install() )
 					$newblog = 'http://' . $current_site->domain . $current_site->path . $newblogname . '/';
 				else
 					$newblog = 'http://' . $newblogname . '.' . $current_site->domain . $current_site->path;