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In computer networking, the multicast Domain Name System (mDNS) resolves host names to IP addresses within small networks that do not include a local name server. It is a zero-configuration service, using essentially the same programming interfaces, packet formats and operating semantics as the unicast Domain Name System (DNS). While designed by Stuart Cheshire to be stand-alone capable, it can work in concert with unicast DNS servers.〔.〕 The mDNS protocol is published as RFC 6762, uses IP multicast User Datagram Protocol (UDP) packets, and is implemented by the Apple Bonjour and by Linux nss-mdns services. mDNS can work in conjunction with DNS Service Discovery (DNS-SD), a companion zero-configuration technique specified separately in RFC 6763.〔 〕 == Protocol overview == When an mDNS client needs to resolve a host name, it sends an IP multicast query message that asks the host having that name to identify itself. That target machine then multicasts a message that includes its IP address. All machines in that subnet can then use that information to update their mDNS caches. Any host can relinquish its claim to a domain name by sending a response packet with a time to live (TTL) equal to zero. By default, mDNS only and exclusively resolves host names ending with the .local top-level domain (TLD). This can cause problems if that domain includes hosts which do not implement mDNS but which can be found via a conventional unicast DNS server. Resolving such conflicts requires network-configuration changes that violate the zero-configuration goal.抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Multicast DNS」の詳細全文を読む スポンサード リンク
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