You can't do this in the protocol (DNS) itself directly. If you could mirror the site, then you could simply create two address recource records (RR) pointing to both of them, then you'd be using both more or less equally. Clients would essentially round robin between the two. To implement an idle system and failover, you would need some sort of monitor on the main site that would trigger an update of the DNS address record when a failure is detected.
If you run the DNS server yourself, you could accomplish this with some relatively straight forward scripting fu. In a nutshell, a cron process would check connectivity of the primary site. If it detects a failure, it updates the zone with the back up server.
Some DNS service providers offer this service, often at a cost, which may be more elegant than doing it yourself.
now the question is ... can i have my domain name "Forexef.com" point to multiple hosting spaces , for example it uses "Arvixe" as the primary and if it fails it directs to hostgator .
if that's possible any advice about how to do it would be highly appreciated ...
In a word yes.
You will need to engage the services of a dns services provider that has monitoring and failover features as part of the feature set. In some cases you can also do throttling by using custom response coding when the monitor requests hit your page.
The provider should have documentation on your usage case that you can follow.