Responder is an LLMNR, NBT-NS and MDNS poisoner. It will answer to
specific NBT-NS (NetBIOS Name Service) queries based on their name
suffix (see: http://support.microsoft.com/kb/163409). By default, the
tool will only answer to File Server Service request, which is for SMB.

The concept behind this is to target our answers, and be stealthier on
the network. This also helps to ensure that we don't break legitimate
NBT-NS behavior. You can set the -r option via command line if you want
to answer to the Workstation Service request name suffix.