avahi-resolve-host-name

View documentation for the original command

$ tldr avahi-resolve

avahi-resolve-host-name [OPTIONS] HOSTNAME

-4, --ipv4
    Resolve IPv4 addresses only. If specified, the command will only look for and return IPv4 addresses for the given hostname.

-6, --ipv6
    Resolve IPv6 addresses only. If specified, the command will only look for and return IPv6 addresses for the given hostname.

-v, --verbose
    Enable verbose output. This provides more detailed information about the resolution process, which can be helpful for debugging.

-t , --timeout=
    Set the query timeout in milliseconds. The command will wait for a response for this duration before giving up. A value of 0 means no timeout.

avahi-resolve-host-name is a command-line utility from the Avahi project, an open-source implementation of Zeroconf (also known as Bonjour or Apple's service discovery technology). Its primary function is to resolve hostnames that are discoverable via Multicast DNS (mDNS) on the local network into their corresponding IP addresses (IPv4 or IPv6).

Unlike traditional DNS, which relies on a central server, mDNS operates by sending multicast queries to all devices on the local subnet. Devices that recognize the queried hostname respond directly with their IP address. This makes avahi-resolve-host-name particularly useful for discovering devices like network printers, smart home appliances, or other computers (e.g., Raspberry Pis) that advertise themselves using .local hostnames, without needing a dedicated DNS server configuration.

The command queries the Avahi daemon, which manages mDNS services, to perform the hostname resolution. It provides a quick and convenient way to check the network presence and IP address of mDNS-enabled devices.

• Requires the Avahi daemon (avahi-daemon) to be running and properly configured on the system for optimal operation.
• Primarily resolves hostnames ending in .local, which are standard for mDNS. It does not resolve traditional DNS names.
• Relies on multicast networking (UDP port 5353) to be enabled and not blocked by firewalls on the local network segment.
• Resolution only works for devices advertising their presence via mDNS.

avahi-resolve-host-name is invaluable in environments where devices are frequently added or removed without fixed IP addresses, or in home networks where a dedicated DNS server might not be present. Common use cases include:

• Discovering IoT Devices: Finding the IP address of smart home devices that advertise themselves via mDNS.
• Accessing Raspberry Pis/SBCs: Easily connecting to single-board computers (e.g., raspberrypi.local) without knowing their dynamically assigned IP address.
• Network Printer Discovery: Locating and connecting to network-enabled printers that support Bonjour/mDNS.
• Ad-hoc Network Configuration: Facilitating communication between devices on a local network without manual IP configuration.

When you run avahi-resolve-host-name, it typically communicates with the local Avahi daemon (avahi-daemon). The daemon then sends out a Multicast DNS (mDNS) query on the local network (UDP port 5353, destination IP 224.0.0.251 for IPv4 or ff02::fb for IPv6). Any device on the network that identifies with the queried hostname will respond directly to the host that sent the query, providing its IP address. The Avahi daemon receives this response and passes it back to the avahi-resolve-host-name command, which then displays the resolved IP address to the user.

The Avahi project was initiated by Lennart Poettering (known for PulseAudio and systemd) and others, aiming to provide an open-source implementation of Apple's Zeroconf (Bonjour) networking technology for Linux and other Unix-like systems. It was developed to enable automatic discovery of services and devices on a local network without manual configuration or a central DNS server. avahi-resolve-host-name is a foundational utility within this suite, providing direct hostname-to-IP resolution capabilities that leverage the mDNS protocol.

avahi-browse(1), avahi-daemon(8), host(1), dig(1), nslookup(1), ping(8)