---
title: "EnableMulticast 0: disabling LLMNR in Windows"
description: "LLMNR lets PCs on the same network resolve each other's names by multicast when DNS has no answer. What it changes, when it hurts, and how to undo it."
url: https://frozentweaks.com/tweaks/disable-llmnr
author: Frost LIVE, Founder of Frozen Tweaks
published: 2026-10-08
updated: 2026-10-08
category: "Network"
source: Frozen Tweaks (https://frozentweaks.com)
---

# EnableMulticast 0: disabling LLMNR in Windows

**Short answer:** LLMNR lets PCs on the same network resolve each other's names by multicast when DNS has no answer. It is also a well known route for spoofing attacks. The EnableMulticast policy set to 0 turns it off. In the registry it sets EnableMulticast to 0 under HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient.

## In the app

- Switch: Disable LLMNR (Network, Pro, Advanced)
- Undo: Yes. Switching it off puts back exactly what was there before, value for value.
- Catalog row: https://frozentweaks.com/tweaks#t-1150

## What it does

LLMNR lets PCs on the same network resolve each other's names by multicast when DNS has no answer. It is also a well known route for spoofing attacks. The EnableMulticast policy set to 0 turns it off.

In the app the switch is called "Disable LLMNR", described there as: Turns off legacy multicast name lookups: less broadcast traffic and one known spoofing route gone.

## When it helps

- Security on shared networks, and slightly less multicast traffic.

## When it hurts

- On a network without a local DNS server, reaching another PC by its name alone can fail. Its IP address still works.

## What it writes

Read from the app's source. "Switching it off" is what the app writes when you turn the tweak off again.

Registry values:

| Key | Value | With the tweak | Switching it off |
| --- | --- | --- | --- |
| `HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient` | `EnableMulticast` | `0` | Your previous value (saved before the change, or deleted if there was none) |

Source: Tweaks/pack_extra.hpp in the app's source, app 2.0.0, checked 2026-10-08.

## The same change by hand

Run in a Command Prompt opened as administrator. Make a restore point first.

```bat
reg add "HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient" /v "EnableMulticast" /t REG_DWORD /d 0 /f
```

See what it is set to now:

```bat
reg query "HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient" /v "EnableMulticast"
```

## How to undo it

Switch the tweak off in Frozen Tweaks. The app saved what each value was before the change and writes exactly that back, or removes the value if it did not exist.

## Verdict

A standard hardening setting. It is not a latency tweak.

## Questions

### What does the "Disable LLMNR" tweak change in Windows?

In the registry it sets EnableMulticast to 0 under HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient.

### Is "Disable LLMNR" safe to switch on?

A standard hardening setting. It is not a latency tweak. The main cost: On a network without a local DNS server, reaching another PC by its name alone can fail. Its IP address still works.

### How do I undo it?

Switch the tweak off in Frozen Tweaks. Switching it off puts back exactly what was there before, value for value.

### Is "Disable LLMNR" free in Frozen Tweaks?

It is part of Frozen Pro and Elite. You can also make the change by hand with the values on this page.

## Related guides

- [How to Reduce Input Lag on PC: The Whole Latency Chain](https://frozentweaks.com/guides/reduce-input-lag)
- [Windows 11 Gaming Optimization: What Still Works in 2026](https://frozentweaks.com/guides/windows-11-gaming-optimization)

## More tweak explainers

- [NetworkThrottlingIndex](https://frozentweaks.com/tweaks/network-throttling-index)
- [Nagle's algorithm](https://frozentweaks.com/tweaks/disable-nagle-algorithm)
- [Delivery Optimization](https://frozentweaks.com/tweaks/disable-delivery-optimization)

---
Written by Frost LIVE, founder of Frozen Tweaks. Canonical version: https://frozentweaks.com/tweaks/disable-llmnr