Hello,
Yes you can do that with ARR
In IIS manager click on your server node (not a web site) in the left tree and from there open "Application Request Routing"
On that page check the "Enable proxy" check box at the top. Still on that page, in the "Proxy Type" section at the bottom make sure the "Use URL Rewrite to inspect incoming requests" is checked and add serveur1 in the Reverse proxy text box. Click Apply to save your changes.
This will create a URL rewrite rule that will redirect all incoming requests to serveur1.
Now we are going to modify this rules and add other rules for the other servers.
Click on your server node again and open "URL Rewrite". There you should see a rule called ARR_server_proxy. This is the basic rule that was created previously.
Select that rule and click edit. Everything on that page should be good to route requests to serveur1 but it's missing the condition to route only the requests coming in for www.domain.com. So add a new condition with the following input values
Condition input: {HTTP_HOST}
Check if input string: Matches the pattern
Pattern: www.domain.com
Now click ok and Apply to save your rule.
This rule will now route every requests for www.domain.com to serveur1.
From there you should go back to the rules page and add new rules identical to this one but with conditions for your other domain names and the other servers.
You can check at the bottom of this page to see all of the HTTP headers and server variables you can use in conditions.
http://learn.iis.net/page.aspx/510/achieving-high-availability-and-scalability---arr-and-hardware-load-balancer/
Bonne chance!