I agree with tiedeman, a dba is an important first to starting a business. It does not prove you are a business or are in business. Also it does not give you the rights to a particular name. You don't need a dba to get your local business license. More than one company can have the same dba in the same area. The only way to try to stop others from using your company name is to be the first in your area with that dba and then sue anybody who pops up after you do, but suing them is no guaranty. To have the "rights" to be the only one with your name would be to have it registered as a trademark.
Jeff@Family Lawn Care