At a customer of mine we had problems with the SharePoint Search. The problem was stated as the search is not working correctly it shows content of different countries in different sites and not the content of the site.
After searching a lot we found out that the search was working correclty but it was in the code. Someone picked code somewhere from the net and did not know what it was doing at all. In our case the scope was stated in some page in the layouts directory and it was stated to dutch In most Countries. this explained why it came back with these results.
So that was a easyone at the end.
That is just the intro of this post. Why was it hard to find well first of all we had no access to the server and all is done by a hosting party with a virtual room. What i found when we looked at the Shared service is that there was only 1 content source for over 21 sites(countries). It would take over a hour to do the crawl, and it is not easy to find the errors.
We would like to make a content source of every site wich has to be crawled. Why? if you split the content source up it is more easy to find problems. And like in our case new sites are edited you don't have to do the crawl again.
So how do you set this settings? In my screenshots i forgot the Http:// so please do not forget this with configuring
Step one go to central admin:
Go to the Shared Service Provider in this case Sharedservices:

Go to search settings Located under Search
Go to content sources and crawl schedules:

at the moment it looks like this if click next to the name a dropdownbox shows click on edit:

As you can see in begin addresses it states in my case 3 sites this should only be one. Like this:

Click create the schedule and click ok. state the scope only Sharepoint or more....
After returning to the page Click on new Content Source

It opens a add content source page I would suggest to give it the name of the site you want to crawl.
In my case it is www.example.be leave the radio button on SharePoint sites since we only index this at the moment give the url inc.http:// and at a schedule it will look like this:

These steps have to be repeated for all sites. And offcourse you have to crawl site by site or have a good schedule in place this will decrease to load on the server and make your enviremont perform better