> ## Documentation Index
> Fetch the complete documentation index at: https://number0-improve-contact.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# mDNS

The mDNS address lookup mechanism will automatically broadcast your endpoint's
presence on the local network, and listen for other endpoints doing the same. When
another endpoint is discovered, the dialing information is exchanged, and a
connection can be established directly over the local network without needing a relay.

Devices need to be connected to the same local network for mDNS address lookup to
work. This can be a Wi-Fi network, an Ethernet network, or even a mobile
hotspot. mDNS is not designed to work over the internet or across different
networks.

<Frame>
  <img src="https://www.iroh.computer/animations/mdns-address-lookup.svg" alt="Three devices on the same network — an iPhone, an Android phone and an embedded device — behind one router; each multicasts an mDNS announcement of its key and local address, and every device's known-peers list grows as the announcements arrive" style={{ width: '100%' }} />
</Frame>

## Usage

mDNS address lookup is not enabled by default. It lives in the separate
[`iroh-mdns-address-lookup`](https://crates.io/crates/iroh-mdns-address-lookup)
crate, which you add alongside `iroh`.

```toml theme={null}
[dependencies]
iroh = "1"
iroh-mdns-address-lookup = "0.4"
```

Add the `MdnsAddressLookup` to the endpoint with `Endpoint::builder`. We run it next to the default DNS address lookup, so connections still work when the two endpoints are not on the same local network.

```rust theme={null}
use iroh::{Endpoint, endpoint::presets};
use iroh_mdns_address_lookup::MdnsAddressLookup;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let endpoint = Endpoint::builder(presets::N0)
        .address_lookup(MdnsAddressLookup::builder())
        .bind()
        .await?;
    // your code here
    Ok(())
}
```

For more on how mDNS address lookup works, see the [`iroh-mdns-address-lookup` documentation](https://docs.rs/iroh-mdns-address-lookup).