mDNS Service Discovery: Browse and Resolve Local Network Services

mDNS (Multicast DNS) and DNS‑SD (Service Discovery) power zero‑configuration networking — printers, cameras, IoT devices, smart home hubs, media servers, and development boards all advertise themselves automatically on the local network. The mDNS Connector allows your workflows to discover and resolve these services without needing IP addresses or manual configuration.

The connector definition states that it can "discover and query zero‑configuration services on the local network via mDNS/DNS‑SD." It supports browsing service types and resolving specific service instances.

Step 1: Browse Available Services

Drag a Browse Services node onto the canvas. This action sends a multicast PTR query and listens for responses for a configurable number of seconds.

Configure the following settings:

• serviceType — e.g., _http._tcp.local, _printer._tcp.local, _hap._tcp.local
• waitSeconds — how long to collect responses
• networkIface — optional local interface IP (default: all)

On success, Nodlyn returns:

• address — sender IP
• instance — first label extracted from the response
• count — number of discovered services

This is ideal for discovering printers, HomeKit devices, MQTT brokers, cameras, or any service that advertises via mDNS.

Step 2: Resolve a Specific Service

Use the Resolve Service node to obtain detailed information about a specific mDNS instance. The executor sends an ANY query and waits for SRV, A/AAAA, and TXT records.

Configure:

• instanceName — e.g., My Printer._http._tcp.local
• waitSeconds — timeout for collecting responses

Outputs include:

• address — resolved IPv4/IPv6 address
• port — service port
• txt — TXT record key/value pairs
• resolved — true when IP + port were found

This is perfect for connecting to local APIs, configuring devices, or building dynamic network workflows.

Step 3: Understand What mDNS Returns

The connector extracts the following DNS‑SD record types:

• A — IPv4 address
• AAAA — IPv6 address
• SRV — port and target host
• TXT — metadata fields

TXT records often include useful information such as:

• device model
• version
• authentication flags
• API endpoints
• configuration hints

Step 4: Build Network‑Aware Automations

Once mDNS data enters your workflow, you can combine it with any other connector:

• Automatically detect devices when they appear on the network
• Resolve service endpoints and send HTTP requests
• Trigger alerts when new devices join
• Store discovery results in Google Sheets or databases
• Build dashboards showing active services

mDNS becomes a powerful discovery mechanism inside your automation ecosystem.

Example Workflow

Here’s a complete mDNS automation you can build:

1. Browse for _http._tcp.local services.
2. Resolve each discovered instance to IP + port.
3. Send an HTTP request to each device’s API.
4. Store the results in a database.
5. Notify operators when new devices appear.

All of this runs automatically — no manual network scanning required.

What's Next?

Try combining mDNS with connectors like HTTP, WebSocket, or OPC UA. Build dynamic discovery systems, smart home automations, or network monitoring dashboards.

mDNS unlocks powerful zero‑configuration networking — and this connector makes it simple, safe, and deeply integrated.