A corrupted hosts file can cause website loading issues or incorrect redirects; the fix involves restoring it to its default state with only localhost entries. 2. On Windows, open Notepad as administrator, navigate to C:\Windows\System32\drivers\etc\, edit the hosts file by removing suspicious entries and keeping only "127.0.0.1 localhost" and "::1 localhost", save the file, then run "ipconfig /flushdns" in an admin Command Prompt. 3. On macOS, open Terminal, run "sudo nano /etc/hosts", remove unwanted lines while preserving the localhost entries, save with Ctrl O and exit with Ctrl X, then flush the DNS cache using "sudo dscacheutil -flushcache" and "sudo killall -HUP mDNSResponder" for newer versions. 4. On Linux, use "sudo nano /etc/hosts" to edit the file, clean it to retain only the essential localhost mappings, optionally keep "127.0.1.1 your-computer-name", save and exit, then flush the DNS cache via "sudo systemd-resolve --flush-caches" if using systemd-resolved or restart networking services. 5. Prevent future issues by avoiding untrusted software, using antivirus tools, backing up the clean hosts file, and checking it when connectivity problems arise; if a backup exists, restore it with proper permissions to ensure system stability.
A corrupted or misconfigured hosts file can cause issues like websites not loading, being redirected incorrectly, or certain services failing to connect. The hosts file is a simple text file used by your operating system to map hostnames (like google.com) to IP addresses — and if it's been altered by malware, software, or manual errors, it may need fixing.

Here’s how to fix a corrupted hosts file on Windows, macOS, and Linux.
? 1. Understand What a Clean Hosts File Should Look Like
Before making changes, know what a default (clean) hosts file contains:

# Copyright (c) 1993-2009 Microsoft Corp. # # This is a sample HOSTS file used by Microsoft TCP/IP for Windows. # # This file contains the mappings of IP addresses to host names. Each # entry should be kept on an individual line. The IP address should # be placed in the first column followed by the corresponding host name. # The IP address and the host name should be separated by at least one # space. # # Additionally, comments may be inserted on individual lines or following # the machine name denoted by a '#' symbol. # # For example: # # 102.54.94.97 rhino.acme.com # source server # 38.25.63.10 x.acme.com # x client host 127.0.0.1 localhost ::1 localhost
That’s it — usually just two active lines mapping localhost
to the IPv4 and IPv6 loopback addresses.
If your file has hundreds of entries, redirects to strange IPs, or blocks common domains (like google.com
, microsoft.com
), it may be corrupted or hijacked.

?? 2. Fix the Hosts File on Windows
Step-by-step:
Open Notepad as Administrator
- Press
Start
, search for Notepad. - Right-click > Run as administrator.
- Press
Open the hosts file
- In Notepad, go to File > Open.
- Navigate to:
C:\Windows\System32\drivers\etc\
- Change file filter from "Text Documents (*.txt)" to "All Files".
- Open the file named hosts (no extension).
Clean the file
- Delete any suspicious or unwanted entries.
- Keep only:
127.0.0.1 localhost ::1 localhost
- Optionally, you can comment out bad lines with
#
instead of deleting them.
Save the file
- Click Save.
- If you get a permission error, make sure Notepad is running as admin.
Flush DNS cache
- Open Command Prompt as admin.
- Run:
ipconfig /flushdns
? 3. Fix the Hosts File on macOS
Step-by-step:
Open Terminal
- Go to Applications > Utilities > Terminal.
Edit the hosts file
- Run:
sudo nano /etc/hosts
- Enter your password when prompted.
- Run:
Remove unwanted entries
- Use arrow keys to navigate.
- Delete any suspicious lines (e.g., redirects, blocked sites).
- Ensure these lines are present:
127.0.0.1 localhost ::1 localhost
Save and exit
- Press
Ctrl O
→ Enter to save. - Press
Ctrl X
to exit.
- Press
Flush DNS cache
- On macOS Ventura or later:
sudo dscacheutil -flushcache sudo killall -HUP mDNSResponder
- On older versions, use:
sudo killall -HUP mDNSResponder
- On macOS Ventura or later:
? 4. Fix the Hosts File on Linux
Step-by-step:
Open Terminal
Edit the hosts file
sudo nano /etc/hosts
Clean the content
- Remove any malicious or incorrect entries.
- Keep the essential lines:
127.0.0.1 localhost ::1 localhost 127.0.1.1 your-computer-name # (common on Ubuntu, optional)
Save
Ctrl O
to write out,Enter
, thenCtrl X
to exit.
Flush DNS (depends on distro)
- If using
systemd-resolved
:sudo systemd-resolve --flush-caches
- On other systems, restart networking or use:
sudo /etc/init.d/dns-clean restart
? 5. How to Prevent Future Corruption
- Avoid sketchy software: Some adware or "optimizers" modify the hosts file.
- Use antivirus tools: Regular scans can catch malware that alters system files.
- Back up the hosts file: After cleaning, save a known-good copy.
- Monitor changes: If websites suddenly stop working, check the hosts file first.
Optional: Restore from a Known-Good Backup
If you have a backup of a working hosts file, simply replace the current one:
- Windows: Paste into
C:\Windows\System32\drivers\etc\
- macOS/Linux: Replace
/etc/hosts
withsudo cp backup_hosts /etc/hosts
Make sure to set proper permissions afterward (usually readable by all, writable only by root/admin).
Basically, fixing a corrupted hosts file comes down to editing it with admin/root privileges, removing bad entries, and flushing the DNS cache. It's not complex — but easy to overlook when troubleshooting network issues.
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