I found very interesting article on connection pooling in ASP.net.
If you want to understand what is connection pooling,
It gives solid proof of what exactly happens when you open connection with your Data base server using ADO.net
default size of pool is 100.
you can also check with below query and perform the tests described in that article.
Using below query you can check number of connections opened to database and who opened it etc..
select db_name(dbid) as DataBaseName , count(dbid) as NoOFConnections , loginame as LoginName from sys.sysprocesses
where dbid > 0
group by dbid,loginame
SELECT spid, uid=rtrim(loginame), Program_name=rtrim(Program_name),
dbname=db_name(dbid), status=rtrim(status) FROM master.dbo.sysprocesses
WHERE loginame = 'sa' and db_name(dbid) = 'APITest'
order by dbname
To know, which connction string I should use with what data base providers.