How to Refresh the Hosts File on a Mac

The Hosts file on a Mac is a plain text file that maps hostnames to IP addresses. It can be useful for various purposes, such as blocking websites or redirecting domain names. If you’ve made changes to your Hosts file and they’re not taking effect, you may need to refresh the file or clear the DNS cache. Here’s how you can do it using the Terminal:

1. Open Terminal: You can find Terminal in the Utilities folder within the Applications folder, or you can quickly access it using Spotlight (Cmd + Space, then type “Terminal”).

2. Edit the Hosts File (if necessary): If you need to make changes to the Hosts file, you can do so with a text editor like nano or vim. For example:

   1	sudo nano /etc/hosts

   This command will open the Hosts file in the nano text editor with superuser privileges. You’ll need to enter your admin password.

3. Make Your Changes: Add, edit, or remove entries in the Hosts file as needed. Each entry should be in the format IP_Address Hostname. For example:

   1	127.0.0.1 localhost

4. Save the File: In nano, press Ctrl + O to save the file, then press Enter. To exit nano, press Ctrl + X.

5. Clear the DNS Cache: To ensure that your changes take effect immediately, you can flush the DNS cache by running the following command:

   1	sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

   This command flushes the DNS cache and restarts the mDNSResponder process.

6. Verify Your Changes: You can verify that your Hosts file changes have taken effect by opening a web browser and entering the hostname you modified. It should now resolve to the IP address you specified in the Hosts file.

Keep in mind that modifying the Hosts file can have important implications for your system’s network behavior, so use it with caution. Make sure you know what you’re doing and back up the original Hosts file before making changes.

That’s it! You’ve successfully refreshed the Hosts file on your Mac and cleared the DNS cache to ensure that your changes are applied.