I was reading an article over the weekend where the author pointed out that the standard naming convention for SQL Server database files was .MDF for the data file, LDF for the log file and NDF for additional data files.  This was good stuff so far, then the author stated that these can be changed if you want to mess around with your other DBA’s.  I have known for years that the file extensions are merely suggestions (best practice) and that you could change them if you so chose.  Some companies may have policies defined that data files must have an extension of .001 and logs .002, etc.

What I wish the author had pointed out was that if you deviate from what is standard for file extension naming for your data and log files, please make sure your security department adds those new extensions to the list of excludes for your virus protection.  If not, you will have successfully launched a denial of service (DOS) attack against yourself.