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LibrariesinsideNetworking basics

Updated Jul 2025

mDNS

mDNS stands for Multicast Domain Name Systemexternal_link, which is a form of domain name resolution.

mDNS is a variation of DNS service, which is a form of domain name resolution. When an mDNS client needs to resolve a hostname, it sends an IP multicastexternal_link query message that asks the host that has that name to identify itself.

An mDNS message is a multicast UDP packet sent using the following addressing:

If ipconfigUSE_DNS and ipconfigUSE_MDNS are set to 1 in FreeRTOSIPConfig.h then the FreeRTOS-Plus-TCP API function FreeRTOS_gethostbyname() can be used to resolve a text name to an IP address when the hostname has a postfix ".local".