Should connection string in web.config file be encrypted?

hi,

if you want to hide connection string detail then you may encrypt it, but it is not necessary .

Please refer
http://www.codeproject.com/Tips/304638/Encrypt-or-Decrypt-Connection-Strings-in-web-confi
http://chiragrdarji.wordpress.com/2008/08/11/how-to-encrypt-connection-string-in-webconfig/

major disadvantages with encrypted connection string is you can not change connection string easily but have put some extra afford on to do this.
also run you have put extra logic to decrypt connection string before it pass to connection.

hope this will help you.