NBNS performs the same function as LLMNR, but using UDP broadcast packets instead of multi cast packets. Browsers normally only attempt to use NBNS after attempts to use LLMNR have failed.

ipconfigUSE_NBNS must be set to 1 in FreeRTOSIPConfig.h for NBNS to be enabled. As with LLMNR, the application writer must provide the xApplicationDNSQueryHook() callback function which takes a character pointer as a parameter and returns pdTRUE if the name passed into the function matches a name used to identify the node.