Why SQL Server drops connection
Some days ago my client asked me why 2 workstations loosing connection every 30 minutes. Only restart of PC (!) helps to run application again! First guess was that something wrong with network for these PCs, but no, network was ok. Finally he noticed that DNS settings are different, both DNS servers are the same, one - local server and other – external, but in other order. Don’t know which one exactly caused this problem, but certainly this is not a good configuration, I would better leave only one, local server, as DNS server, and let it decide how to deal with external DNS requests.
Anyway – another option is to run Cliconfg and create an alias to SQL Server using TCP/IP library and its IP address, this always works fine for me.