The mDNS library implements the DNS-SD/mDNS discovery mechanism for services. This library comes in different forms, depending on the operating system:

Usually, programmers need not use the mDNS library directly. In fact, they are disencouraged to do so, since different service discovery mechanisms may be used in the future. Also, most of the functionality provided by mDNS is wrapped in a much more convenient to use API in the TJScout library.