esphome / esphome/feature-requests

Set mDNS TTL

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Description

**Describe the problem you have/What new integration you would like**

I access a remote HomeAssistant network via ZeroTier and observe MDNS requests from that remote HomeAssistant network outside the network.

The ESPHOME mDNS application appears to set the TTL of mDNS requests == 255 which causes ZeroTier to propagate the mDNS requests further into the private network. This causes MDNS requests from all hosts and networks that are connected to the ZeroTier private network to appear in all connected hosts which increases MDNS traffic unnecessarily and violates the basis of mDNS.

An additional problem is that mDNS queries are emitted even though the device in the remote network has a static IP address configured.

I would like to be able to set the mDNS TTL (typically == 1) so that it is not propagated outside the remote HomeAssistant network by ZeroTier.
When using static IP for the ESPHOME node no MDNS queries should be emitted.

**Please describe your use case for this integration and alternatives you've tried:**

I have set a static address for a device in a remote HomeAssistant network that I can access via ZeroTier. Using Wireshark the MDNS queries for an ESPHOME device in the remote HomeAssistant network can be seen on the Zerotier virtual interface of my local computer that is used to access the remote network.
The ideal would be, if TTL == 1, that ZeroTier honors the TTL and does not propagate the MDNS packet beyond the remote HomeAssistant network.

**Additional context**

I suspect that the concept of TTL (that sets the allowable number of network hops) in TCP/IP networking can be confused with the concept of TTL (which sets the time before a DNS entry is refreshed) in "regular" DNS. This might have to be highlighted in a solution to this problem.

Contributor guide

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Research direction

The request identifies ESPHome mDNS behavior, ZeroTier propagation, and static IP configuration, but names no files, tests, or entry points. Start by locating the mDNS and static-IP handling; done means supporting a configurable mDNS TTL and emitting no mDNS queries when a static address is configured.

Written by the indexing model from the issue text.

Assessment

Domain
embedded-iot, networking
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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