diff --git a/modules/admin/admin.admin.controller.php b/modules/admin/admin.admin.controller.php
index b67bef555..cbaa546db 100644
--- a/modules/admin/admin.admin.controller.php
+++ b/modules/admin/admin.admin.controller.php
@@ -1039,13 +1039,17 @@ class adminAdminController extends admin
 			'html_footer' => $vars->html_footer,
 		);
 		
+		// Get the DB object and begin a transaction.
+		$oDB = DB::getInstance();
+		$oDB->begin();
+		
 		// Insert or update the domain.
 		if (!$domain_info)
 		{
 			$args = new stdClass();
-			$args->domain_srl = getNextSequence();
+			$args->domain_srl = $domain_srl = getNextSequence();
 			$args->domain = $vars->domain;
-			$args->is_default_domain = 'N';
+			$args->is_default_domain = $vars->is_default_domain === 'Y' ? 'Y' : 'N';
 			$args->index_module_srl = $vars->index_module_srl;
 			$args->index_document_srl = $vars->index_document_srl;
 			$args->http_port = $vars->http_port;
@@ -1064,6 +1068,7 @@ class adminAdminController extends admin
 			$args = new stdClass();
 			$args->domain_srl = $domain_info->domain_srl;
 			$args->domain = $vars->domain;
+			$args->is_default_domain = $vars->is_default_domain === 'Y' ? 'Y' : 'N';
 			$args->index_module_srl = $vars->index_module_srl;
 			$args->index_document_srl = $vars->index_document_srl;
 			$args->http_port = $vars->http_port;
@@ -1077,18 +1082,30 @@ class adminAdminController extends admin
 			}
 		}
 		
+		// If changing the default domain, set all other domains as non-default.
+		if ($vars->is_default_domain === 'Y')
+		{
+			$args = new stdClass();
+			$args->not_domain_srl = $domain_srl;
+			$output = executeQuery('module.updateDefaultDomain', $args);
+			if (!$output->toBool())
+			{
+				return $output;
+			}
+		}
+		
 		// Save the favicon, mobicon, and default image.
 		if ($vars->favicon || $vars->delete_favicon)
 		{
-			$this->_saveFavicon($args->domain_srl, $vars->favicon, 'favicon.ico', $vars->delete_favicon);
+			$this->_saveFavicon($domain_srl, $vars->favicon, 'favicon.ico', $vars->delete_favicon);
 		}
 		if ($vars->mobicon || $vars->delete_mobicon)
 		{
-			$this->_saveFavicon($args->domain_srl, $vars->mobicon, 'mobicon.png', $vars->delete_mobicon);
+			$this->_saveFavicon($domain_srl, $vars->mobicon, 'mobicon.png', $vars->delete_mobicon);
 		}
 		if ($vars->default_image || $vars->delete_default_image)
 		{
-			$this->_saveDefaultImage($args->domain_srl, $vars->default_image, $vars->delete_default_image);
+			$this->_saveDefaultImage($domain_srl, $vars->default_image, $vars->delete_default_image);
 		}
 		
 		// Update system configuration to match the default domain.
@@ -1105,6 +1122,9 @@ class adminAdminController extends admin
 			Rhymix\Framework\Config::save();
 		}
 		
+		// Commit.
+		$oDB->commit();
+		
 		// Clear cache.
 		Rhymix\Framework\Cache::clearGroup('site_and_module');
 		
diff --git a/modules/admin/lang/en.php b/modules/admin/lang/en.php
index a3eaf686d..c6a8a6ef3 100644
--- a/modules/admin/lang/en.php
+++ b/modules/admin/lang/en.php
@@ -118,6 +118,7 @@ $lang->cmd_index_document_srl = 'Main Document';
 $lang->cmd_default_language = 'Default Language';
 $lang->cmd_new_domain = 'Add New Domain';
 $lang->cmd_edit_domain = 'Edit Domain';
+$lang->cmd_is_default_domain = 'Default Domain';
 $lang->about_use_ssl = 'Selecting \'Optional\' is to use SSL for the specified actions such as signing up and changing information.<br />Selecting \'Always\' is to use SSL for the entire pages, generated by Rhymix.<br>Please be careful! You may not be able to access to the site, before installing SSL certificate.';
 $lang->server_ports = 'Server Port';
 $lang->about_server_ports = 'If your web server does not use 80 for HTTP or 443 for HTTPS port, you should specify server ports.';
diff --git a/modules/admin/lang/ko.php b/modules/admin/lang/ko.php
index 85d73a44f..a02342c28 100644
--- a/modules/admin/lang/ko.php
+++ b/modules/admin/lang/ko.php
@@ -117,10 +117,11 @@ $lang->cmd_index_document_srl = '메인 문서';
 $lang->cmd_default_language = '기본 언어';
 $lang->cmd_new_domain = '새 도메인 추가';
 $lang->cmd_edit_domain = '도메인 정보 수정';
+$lang->cmd_is_default_domain = '기본 도메인';
 $lang->about_use_ssl = '\'선택적으로 사용\'은 회원가입, 정보수정 등의 지정된 동작(action)에서만 보안접속(HTTPS)을 사용합니다.<br>\'항상 사용\'은 사이트 전체에 HTTPS를 사용합니다.<br>SSL 인증서가 설치되지 않은 상태에서 HTTPS 사용을 시도하면 접속이 되지 않을 수 있으니 주의하시기 바랍니다.';
 $lang->server_ports = '포트';
 $lang->about_server_ports = 'HTTP는 80, HTTPS는 443 이 아닌, 다른 포트를 사용할 경우에 포트를 지정해 주어야 합니다.';
-$lang->msg_site_title_is_empty = '사이트 이름을 입력해 주십시오.';
+$lang->msg_site_title_is_empty = '사이트 제목을 입력해 주십시오.';
 $lang->msg_invalid_domain = '올바르지 않은 도메인입니다.';
 $lang->msg_domain_already_exists = '이미 등록된 도메인입니다.';
 $lang->msg_invalid_http_port = '올바르지 않은 HTTP 포트입니다.';
diff --git a/modules/admin/tpl/config_domains_edit.html b/modules/admin/tpl/config_domains_edit.html
index 1c882208a..889025d49 100644
--- a/modules/admin/tpl/config_domains_edit.html
+++ b/modules/admin/tpl/config_domains_edit.html
@@ -27,6 +27,10 @@
 			<label class="x_control-label" for="domain">{$lang->domain}</label>
 			<div class="x_controls">
 				<input type="text" name="domain" id="domain" value="{$domain_info ? escape($domain_info->domain) : ''}"/>
+				&nbsp;
+				<label for="is_default_domain" class="x_inline">
+					<input type="checkbox" name="is_default_domain" id="is_default_domain" value="Y" checked="checked"|cond="$domain_info && $domain_info->is_default_domain === 'Y'" disabled="disabled"|cond="$domain_info && $domain_info->is_default_domain === 'Y'" /> {$lang->cmd_is_default_domain}
+				</label>
 			</div>
 		</div>