Say a customer is an observant Jew and wants his site to be offline on Shabat - SEO problem?

Check out how B&H Photo/Video handles this. They allow the site to remain active but inactivate the cart functions.

This handles the no work/commerce on the sabbath.

There will be an SEO issue if you deny access to the content.

Remind your customer that the webserver is not Jewish and doesn't need the day off to go to the local synagogue. The functions of the site can remain active and any incoming inquiries can simply wait until Monday. The customer's physical store can certainly turn everything off and thus will not be "doing business" on Shabbat.

If they really want it "offline" I would do a javascript function to cover the page with a "Closed today" layer rather than disabling the site. If you go that route, also remind the customer that "Saturday" also has to have a timezone attached. Your Saturday morning is someone else's Friday evening.

I haven't thought about this before. But I believe it will probably hurt your SEO but might not if you do it right. You will need to make sure to retrieve a "503 Service Unavailable" http header status, for. Then make sure to tell google or other bots to comeback in X time. To do this you need to create a php file with the script to create a header with the appropiate instructions I will do something like this:

• 1) Create a 503-http-status.php page
• 2) In that page insert the headers information with a php script to tell google to comeback in XX:XX:XX time
• 3) Make sure to write the .htaccess every 7 days or Saturdays with instructions to direct traffic to your 503-http-status.php page. Something like this:

RewriteEngine on
RewriteCond %{REMOTE_ADDR} !^111\.111\.111\.111
RewriteCond %{REQUEST_URI} !/503-http-status.php$ [NC]
RewriteRule .* /503-http-status.php [R=302,L]