Why did it happen (should I be concerned)?

I use SuSE 9.1 on a Windows-dominated network at work. Up to today, the connection with the internet was easy. It was done automatically (DHCP) and the name server was set up automatically. Suddenly, today, I lost contact with the internet and had to add DNS entries to the internet setup using YAST2. What happened to change the situation? Should I be concerned that something else is also amiss? Thanks dj tuchler