What is mdnsresponder on mac?

mDNSResponder is a system daemon in macOS that manages multicast DNS (mDNS) network traffic. mDNS is a protocol that allows devices on a local network to discover and communicate with each other without needing a central DNS server.

mDNSResponder is responsible for resolving hostnames to IP addresses, advertising services on the network, and responding to multicast DNS queries from other devices. It is essential for services like Bonjour, which allows for easy discovery of printers, file sharing, and other network resources on macOS.

mDNSResponder runs in the background on macOS and is typically launched automatically at system startup. Users can monitor and control the behavior of mDNSResponder through the command line using the mdns command, or through the Network Utility app in the System Preferences.

Overall, mDNSResponder plays a crucial role in facilitating seamless network communication and service discovery on macOS devices.