Haven't test it but it should work-
Define two connectionstrings in web.config
<connectionstrings>
<add name="ConStringDQL">
providerName="System.Data.SqlClient"
connectionString= "server=[server1];database=[db name];uid=[user name];pwd=[password]" ></add>
<add name="ConStringDML">
providerName="System.Data.SqlClient"
connectionString= "server=[server2];database=[db name];uid=[user name];pwd=[password]" ></add>
</connectionstrings>
Then create two separate instance of connections using following connection strings
var conStringDQL= ConfigurationManager.ConnectionStrings["conStringDQL"].ConnectionString;
var conStringDML= ConfigurationManager.ConnectionStrings["conStringDML"].ConnectionString;
Now, use
conStringDQL to retrive data and
conStringDML to insert/update data.
Hope, it helps :)