Using IP address to acess website, the arcGIS map services are blank

[DeminHu]

I have a server ,
name: testserver,
alias name: testgis,
IP address: 10.0.1.35

I have arcGIS server on this machine.
I have crossdomain, clientaccesspolicy files under wwwroot.
all arcgis server directories could be accessed by: http://localhost/, http://testserver/, http://testgis/, http://10.0.1.35/
All ArcGIS services  ( rest end point) could be accessed like : http://localhost ( testserver, or testgis, or 10.0.1.35)/arcgis/rest/services/test/mapserver
Test  http://localhost ( testserver, or testgis, or 10.0.1.35)/arcgis/rest/services/test/mapserver/export?jason, the results are fine.

I have Silverlight Application which consumes the map services on this server (actually the application and ArcGIS server on the same machine)

When I access the application by : http://localhost( testserver or  testgis)/TestApp/testpage.aspx, everything is fine.

But when I access the application by : http://10.0.1.35/)/TestApp/testpage.aspx, the application opens, everything not related the map services  is fine, everything related to  the map services  is blank, it seems that security problem blocked the access to the rest end point of the map services. ( bing maps is Ok in the application)

I serached the internet, tried to change crossdomain, clientaccesspolicy files. so far, I still  didn't solve the problem.

Hope somebody could help, many thanks.

[DeminHu]

Just made a little progress,  inside the same firewall, if  access the application by the IP,  in the code of application, call the map service by IP address. if access by the servername, call map service by IP or server name, both of them are fine.

[DominiqueBroux]

If the domain of your SL application is not the same as the domain of your GIS services, you need to add a crossdomain or clientaccesspolicy file to the root of your GIS server.
Thta's true even if the domain difference is just an alias matter.

[DeminHu]

Actually I have these two files under wwwroot. what I  did  for the problem:

1. I changed  the map service URL links by using IP address instead of server names, then the application could be access by IP addrss or server name.
    The strange thing is that:
    If I don't use IP address  for Map service REST URLs, then I get error like: a crossdomain file is needed, a security problem ( actualyl I have a crossdomain  file).
    But  there is no problem for WCF service,   I can use IP address or server name.
  
   However, I don't think this is a solution using IP address for REST urls for the problem, because I have an emergency recover system, I have secondary  ArcGIS server machine which are standbying, if the primary down, I  could not simply switch DNS , I need to manually change the IP addr for my applications( inside code).

2. Worked with network system group, make the  DNS name , alias name available for all people (in different locations) .

Thanks for your kind inputs.