LLMNR is a multicast protocol used on local area networks. It is the method used by all major web browsers to resolve names that do not include a dot ('.'). For example, if you attempt to open the web page: http://my_freertos_device/index.html, then the web browser would send an LLMNR request to try and resolve the name 'my_freertos_device'.

All LLMNR packets are sent to IP address 224.0.0.252 on MAC address 01:00:5E:00:00:FC, so the network interface (MAC) must be programmed to accept packets on that address for LLMNR to function. In addition ipconfigUSE_LLMNR must be defined as 1 in FreeRTOSIPConfig.h, and the user must provide the implementation of a callback function xApplicationDNSQueryHook() that takes a char pointer as a parameter and returns pdTRUE if the name passed into the function matches a name used to identify the node.