Editing Zero-configuration networking (section)

====DNS-SD with multicast====
mDNS uses packets similar to [[Domain Name System#DNS message format|unicast DNS]] to resolve hostnames except they are sent over a multicast link.  Each host listens on the mDNS port, 5353, transmitted to a well-known multicast address and resolves requests for the [[DNS record]] of its ''.local'' hostname (e.g. the [[List of DNS record types#A|A]], [[List of DNS record types#AAAA|AAAA]], [[CNAME]]) to its IP address.  When an mDNS client needs to resolve a local hostname to an IP address, it sends a DNS request for that name to the well-known multicast address;  the computer with the corresponding A/AAAA record replies with its IP address.  The mDNS multicast address is {{IPaddr|224.0.0.251}} for IPv4 and {{IPaddr|ff02::fb}} for IPv6 link-local addressing.

DNS Service Discovery aka [[DNS-SD]] requests can also be sent using mDNS to yield zero-configuration DNS-SD.{{Ref RFC|6763}} This uses DNS [[PTR record|PTR]], SRV, [[TXT record|TXT]] records to advertise instances of service types, domain names for those instances, and optional configuration parameters for connecting to those instances. But SRV records can now resolve to ''.local'' domain names, which mDNS can resolve to local IP addresses.