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What is mDNSResponder on Mac and Is It Safe?.mdnsresponder mac.

Launch Activity Monitor on your Mac and you are bound to find several processes with cryptic labels. We’ve posted a few notes detailing what some of these system processes (WindowServer and kernel_task) are doing on your Mac. In this post, we will talk about mDNSResponder.

What Is mDNSResponder?

mDNSResponder stands for Multicast DNS Responder. It is an essential system application that supports some of the basic functions and capabilities of macOS. If your Mac and another mDNSResponder are on the same network, mDNSResponder is a background process that allows both devices to discover and communicate with each other.

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Yes, the mDNSResponder service may sound unfamiliar to you, but you most likely use it on a daily basis without even realizing it. If you’ve ever connected your Mac to an AirPrint-enabled printer on your local network, mDNSReponder made it possible. This process also makes it easier to find AirPlay-compatible devices (like Apple TV) on your Mac.

mDNSResponder uses the Bonjour networking protocol to automatically identify devices to networked Apple devices.

Bonjour describes the networking technology on which mDNSResponder is built. Bonjour protocol reports the availability of your Mac on the local network. It also allows your device to reliably communicate and communicate using IP addresses.

When connected to a wired or wireless network, Bonjour continually scans the network for other Bonjour-compatible devices. Note that Bonjour works like mDNSResponder on Mac. Although both terms are often used interchangeably, when you start Activity Monitor you will find “mDNSResponder”.

Apps and services (such as iTunes) on third-party devices can also communicate with your Mac using Bonjour. Learn more about how Bonjour works in Windows 10.

Is mDNSResponder Safe?

mDNSResponder is an essential element for the “Bonjour” protocol on Apple devices. This is a legitimate service developed by Apple, so you have nothing to worry about. The process runs in the background and periodically searches for Bonjour-enabled devices on your local network.

Even though it is a safe and hassle-free system process, we have come across some Mac users who reported that mDNSResponder consumes up to 100% CPU usage and slows down Wi-Fi speed.

Here are some fixes to help restore normal mDNSResponder functionality on your Mac.

Fix mDNSResponder Issues

If you’re having an issue with mDNSResponder, you may experience difficulty using file sharing services, media sharing applications, and printer sharing services such as AirPrint. The following fixes may fix crashes affecting mDNSResponder on your Mac.

1. Force exit from mDNSResponder

Forcing mDNSResponder to exit will indeed interrupt the service, but not for long. macOS will immediately restart mDNSResponder because it is a vital system process. However, the operation updates the mDNSResponder and hopefully fixes the issues causing the process to crash.

  1. Start Activity Monitor, double-click mDNSResponder and select Quit.

  1. Select Force End.

Go to the CPU & Networking section of Activity Monitor and verify that forcibly exiting mDNSReponder has stabilized the service. If nothing changes, restart your Mac or boot into Safe Mode.

2. Restart your Mac

Close all active applications, click the Apple logo in the menu bar, and choose Restart. If mDNSResponder continues to work abnormally, try booting your Mac in Safe Mode.

Shut down your Mac and wait until it shuts down completely. After that, press the power button and immediately hold down the Shift key. Release the Shift key when the login window appears.

If your Mac uses an M1 Silicon chip, shut it down and wait for about 10-20 seconds. Then press and hold the power button until the startup options window appears on the screen. Select your preferred boot drive, hold down the Shift key, click Continue in Safe Mode, and release the Shift key when the login screen appears.

Enter your password, restart your Mac normally (Apple logo> Restart) and check if this reduces mDNSResponder’s CPU consumption and network usage.

3. Disable Firewall

Third party firewalls can interfere with devices communicating on your local network. If you are using it, turn it off and check if that solves the problem. You should also make sure that the built-in macOS firewall is not blocking incoming connections.

  1. Go to System Preferences> Security & Privacy> Firewall.
  2. Click the lock icon in the lower left corner, enter your Mac password (or use Touch ID), and click Firewall Options. …

  1. Uncheck “Block all incoming connections” and click “OK”.

4. Disable and enable mDNSResponder

In the rare event that mDNSResponder is using a lot of system resources, disabling and re-enabling the service can fix the problem.

Note. Before re-enabling mDNSResponder, you must temporarily disable System Integrity Protection (SIP). SIP is a security protocol that prevents unauthorized code from executing on macOS.

  1. Go to Finder> Applications> Utilities and launch Terminal.

  1. Paste the command below into a terminal console and press Enter.

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSresponder.plist

  1. Enter your Mac password and press Enter to continue.

Unlike Windows, many macOS apps and services require mDNSResponder to function properly. Therefore, we do not recommend disabling mDNSResponder for too long. Wait a minute and go to the next step to re-enable the service.

sudo launchctl load -w / System / Library / LaunchDaemons / com.apple.mDNSresponder.plist

mDNSResponder Demystified

To summarize, mDNSResponder is a secure process that helps your Mac connect and interact with other devices. If mDNSResponder is not working properly, at least one of the above troubleshooting fixes should normalize it.

What is mDNSResponder on Mac and Is It Safe?

    1. Paste the command below into the console and press Enter.

      1. Enter your Mac password and press Enter.
  1. What is mDNSResponder on Mac and Is It Safe?

mdnsresponder mac

mdnsresponder mac

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