connectionstring in asp.net

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

<connectionStrings>

  

<add  name="cn"

  connectionString="Server=0.0.0.0;

                    Database=db;

                    user=sa;

                    Password=db123"

  providerName="System.Data.SqlClient"/>

                  <!--Server IP Address

                      DatabaseName

                      Database User

                      Database User's Password-->

<add  name="cn"

  connectionString="ADMIN\SQLEXPRESS;

                    Database=db;

                    user=sa;

                    Password=db123"

  providerName="System.Data.SqlClient"/>

                    <!--Your Computer Name

                      DatabaseName

                      Database User

                      Database User's Password-->

</connectionStrings>

</configuration>

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

SqlConnection cn;

cn1 = new SqlConnection(ConfigurationManager.ConnectionStrings["cn"].ConnectionString);