How to stop Google indexing your site when it is under construction or maintenance
change the content of the robots.txt in the root folder to
User-agent: *
Disallow: /
Disallow: /
thats it , google will never look at your site untill you remove these lines. So dont forget to replace these codes with original Joomla robots.txt file contents later.
User-agent: *
Disallow: /administrator/
Disallow: /cache/
Disallow: /components/
Disallow: /images/
Disallow: /includes/
Disallow: /installation/
Disallow: /language/
Disallow: /libraries/
Disallow: /media/
Disallow: /modules/
Disallow: /plugins/
Disallow: /templates/
Disallow: /tmp/
Disallow: /xmlrpc/
Disallow: /administrator/
Disallow: /cache/
Disallow: /components/
Disallow: /images/
Disallow: /includes/
Disallow: /installation/
Disallow: /language/
Disallow: /libraries/
Disallow: /media/
Disallow: /modules/
Disallow: /plugins/
Disallow: /templates/
Disallow: /tmp/
Disallow: /xmlrpc/
Further reading http://antezeta.com/news/avoid-search-engine-indexing
