Why Your Hosts File Changes Disappear After Reboot (and How to Fix It)

You spent time carefully configuring your hosts file, adding all your local development domains, testing everything works perfectly. Then you restart your Mac, and... everything is gone. Your hosts file is back to its default state, all your entries vanished. Sound familiar?

This frustrating scenario is more common than you might think. In this comprehensive guide, we'll explore every reason why your hosts file changes might disappear after a reboot, and provide practical solutions to ensure your configurations persist.

Understanding hosts file persistence

First, let's clarify something important: Under normal circumstances, macOS does NOT automatically reset your hosts file. The /etc/hosts file should persist across reboots just like any other system file. If your changes are disappearing, something specific is causing it.

Reason #1: macOS system updates

The most common cause of hosts file resets is macOS system updates. During major updates, macOS can restore system files to their default state.

When updates reset hosts file

• Major macOS updates (e.g., Ventura → Sonoma)
• Security updates that modify system files
• System file repairs during update process

Why it happens

macOS updates sometimes: 1. Verify system file integrity 2. Restore files to known-good state 3. Overwrite modified system files

The hosts file, being in /etc (system directory), can be affected.

Solution: Backup before updates

Before any macOS update:

# Create timestamped backup
sudo cp /etc/hosts /etc/hosts.backup.$(date +%Y%m%d)

# Also backup to safe location
sudo cp /etc/hosts ~/hosts-backup-$(date +%Y%m%d).txt

After update, restore if needed:

# Check if hosts file was reset
diff /etc/hosts ~/hosts-backup-20260206.txt

# Restore if needed
sudo cp ~/hosts-backup-20260206.txt /etc/hosts
sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

Prevention strategy

1. Always backup before updates 2. Document your entries in a separate file 3. Use version control for hosts configurations 4. Automate backups with scripts or tools

Reason #2: System Integrity Protection (SIP) repairs

System Integrity Protection can repair system files if it detects corruption or unauthorized modifications.

When SIP resets files

SIP might restore /etc/hosts if:

• File permissions are incorrect
• File ownership is wrong
• File integrity check fails
• System detects tampering

Check SIP status

csrutil status

Should show: System Integrity Protection status: enabled.

Verify file integrity

Check if macOS thinks your hosts file is corrupted:

# Check file permissions
ls -la /etc/hosts

# Should show:
# -rw-r--r--  1 root  wheel  /etc/hosts

Solution: Ensure correct permissions

SIP is less likely to reset files with correct permissions:

# Set correct ownership
sudo chown root:wheel /etc/hosts

# Set correct permissions
sudo chmod 644 /etc/hosts

# Verify
ls -la /etc/hosts

If SIP keeps resetting

If SIP repeatedly resets your hosts file:

1. Check system logs for SIP actions: ``bash log show --predicate 'eventMessage contains "hosts"' --last 24h ``

2. Verify no malware is modifying the file 3. Check for conflicting software that might trigger SIP

Reason #3: Time Machine restoration

If Time Machine is backing up your system, it might restore the hosts file from a previous backup.

When Time Machine restores

• Automatic restoration after system issues
• Manual restoration of system files
• Migration Assistant restoring from backup

Check Time Machine status

tmutil listbackups

Solution: Exclude hosts file from restoration

Prevent Time Machine from restoring hosts file:

1. Open System Preferences > Time Machine 2. Click Options 3. Add /etc/hosts to exclusion list

Or use Terminal:

sudo tmutil addexclusion /etc/hosts

Verify exclusion:

tmutil isexcluded /etc/hosts

Manual restoration prevention

When restoring from Time Machine:

• Don't restore system files unless necessary
• Restore hosts file separately after system restoration
• Keep manual backup outside Time Machine

Reason #4: Third-party security software

Antivirus, firewall, or security software might reset the hosts file as a security measure.

Common culprits

• Antivirus software detecting hosts file modifications
• Firewall applications resetting network configs
• Security suites protecting system files
• MDM (Mobile Device Management) policies

Check for security software

# List running processes
ps aux | grep -i "antivirus|security|firewall"

# Check installed profiles
profiles -P

Solution: Configure security software

For each security application:

1. Add exception for /etc/hosts 2. Disable system file protection for hosts file 3. Whitelist hosts file modifications 4. Check logs to see if it's resetting the file

Example - Check if software modified hosts:

# Check file modification time
ls -la /etc/hosts

# Compare with your last edit time
# If modification time is recent but you didn't edit, something else did

Reason #5: Daemon or service overwriting

Some system daemons or services might overwrite the hosts file.

Check for modifying processes

# Monitor file changes
sudo fs_usage -f filesys | grep hosts

This shows processes accessing the hosts file in real-time.

Common daemons to check

• mDNSResponder: Handles DNS, shouldn't modify hosts file
• configd: Network configuration daemon
• networksetup: Network configuration tool

Solution: Identify the culprit

Monitor file access:

# In one terminal, monitor
sudo fs_usage -w -f filesys | grep "/etc/hosts"

# In another terminal, trigger the issue (reboot, etc.)
# Watch which process modifies the file

Check launch daemons:

# List all launch daemons
launchctl list | grep -i "network|dns|host"

# Check specific daemon
launchctl list com.apple.mDNSResponder

Fix daemon issues

If a daemon is overwriting hosts file:

1. Check daemon configuration: ``bash cat /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist ``

2. Restart the daemon: ``bash sudo launchctl kickstart -k system/com.apple.mDNSResponder ``

3. Report the issue if it's an Apple daemon (likely a bug)

Reason #6: File system issues

Corrupted file system or disk errors can cause file resets.

Check disk health

# Check disk
diskutil verifyVolume /

# Repair if needed (in Recovery Mode)
diskutil repairVolume /

Use Disk Utility

1. Open Disk Utility 2. Select your disk 3. Click First Aid 4. Click Run

Solution: Repair file system

If disk errors are found:

1. Backup your data 2. Boot to Recovery Mode (hold Cmd+R during startup) 3. Run First Aid from Disk Utility 4. Restore hosts file from backup after repair

Reason #7: Manual accidental reset

Sometimes the reset isn't automatic—you or someone else might have reset it.

Common scenarios

• System Preferences > Network > Advanced > DNS changes
• Terminal commands that modify /etc/hosts
• GUI tools resetting to default
• Scripts overwriting the file

Solution: Track changes

Enable file monitoring:

# Install fswatch (via Homebrew)
brew install fswatch

# Monitor hosts file
fswatch /etc/hosts | while read f; do
    echo "Hosts file changed at $(date)"
    ls -la /etc/hosts
done

Check modification history:

# Check when file was last modified
stat -f "%Sm" -t "%Y-%m-%d %H:%M:%S" /etc/hosts

# Compare with your memory of when you edited it

Complete persistence strategy

To ensure your hosts file changes never disappear, implement this multi-layered approach:

Layer 1: Regular backups

Automated backup script:

#!/bin/bash
# ~/scripts/backup-hosts.sh

BACKUP_DIR="$HOME/hosts-backups"
mkdir -p "$BACKUP_DIR"

TIMESTAMP=$(date +%Y%m%d_%H%M%S)
BACKUP_FILE="$BACKUP_DIR/hosts-$TIMESTAMP.txt"

sudo cp /etc/hosts "$BACKUP_FILE"
sudo chown $(whoami) "$BACKUP_FILE"

echo "Backed up to: $BACKUP_FILE"

# Keep only last 30 backups
cd "$BACKUP_DIR"
ls -t hosts-*.txt | tail -n +31 | xargs rm -f

Run automatically:

Add to crontab (runs daily):

crontab -e

# Add this line:
0 2 * * * /Users/yourname/scripts/backup-hosts.sh

Layer 2: Version control

Store hosts configurations in Git:

# Initialize repo
mkdir ~/hosts-config
cd ~/hosts-config
git init

# Copy current hosts file
sudo cp /etc/hosts ./hosts.current
sudo chown $(whoami) ./hosts.current

# Commit
git add hosts.current
git commit -m "Initial hosts file backup"

After each edit:

cd ~/hosts-config
sudo cp /etc/hosts ./hosts.current
sudo chown $(whoami) ./hosts.current
git add hosts.current
git commit -m "Updated hosts file $(date +%Y-%m-%d)"
git push  # If using remote repo

Layer 3: Documentation

Keep a separate documented file:

# ~/hosts-entries.txt
cat > ~/hosts-entries.txt << 'EOF'
# My Hosts File Entries
# Last updated: 2026-02-06

# Project Alpha - Development
127.0.0.1    alpha.local
127.0.0.1    api.alpha.local

# Project Beta - Development  
127.0.0.1    beta.local
EOF

Layer 4: Use hosts file manager

GUI tools like Locahl provide:

• Automatic backups before each edit
• Version history of all changes
• Export/import for easy restoration
• Cloud sync (if supported)

Recovery: Restoring lost entries

If your hosts file was reset, here's how to recover:

Step 1: Find your backup

# Check backup directory
ls -la ~/hosts-backups/

# Or check Time Machine
tmutil listbackups

Step 2: Restore from backup

# Restore from manual backup
sudo cp ~/hosts-backups/hosts-20260206_103000.txt /etc/hosts

# Or restore from Time Machine (if available)
sudo tmutil restore /etc/hosts

Step 3: Verify and flush DNS

# Verify contents
cat /etc/hosts

# Flush DNS cache
sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

# Test
ping yourdomain.local

Step 4: Verify permissions

# Ensure correct permissions
sudo chown root:wheel /etc/hosts
sudo chmod 644 /etc/hosts

Prevention checklist

Before any operation that might reset your hosts file:

• [ ] Backup hosts file to safe location
• [ ] Document entries in separate file
• [ ] Commit to version control if using Git
• [ ] Check Time Machine exclusion settings
• [ ] Verify security software won't interfere
• [ ] Test backup restoration process
• [ ] Note modification time before operation

Advanced: Monitoring and alerts

Set up monitoring to detect when hosts file is reset:

File change monitoring script

#!/bin/bash
# ~/scripts/monitor-hosts.sh

LAST_CHECKSUM=$(md5 -q /etc/hosts 2>/dev/null)

while true; do
    sleep 60  # Check every minute
    CURRENT_CHECKSUM=$(md5 -q /etc/hosts 2>/dev/null)
    
    if [ "$LAST_CHECKSUM" != "$CURRENT_CHECKSUM" ]; then
        echo "ALERT: Hosts file changed at $(date)"
        echo "Previous: $LAST_CHECKSUM"
        echo "Current: $CURRENT_CHECKSUM"
        
        # Send notification (requires terminal-notifier)
        # terminal-notifier -message "Hosts file was modified!"
        
        LAST_CHECKSUM=$CURRENT_CHECKSUM
    fi
done

Troubleshooting specific scenarios

Scenario 1: Changes disappear every reboot

Check: 1. Security software resetting file 2. Launch daemon overwriting 3. File system issues 4. Time Machine auto-restore

Solution: Implement backup strategy and identify the resetting process.

Scenario 2: Changes disappear after macOS update

Expected behavior - Always backup before updates.

Solution: Restore from backup after update completes.

Scenario 3: Random resets with no pattern

Check: 1. File monitoring to identify trigger 2. System logs for clues 3. Security software logs 4. Disk health

Solution: Monitor file access and identify the culprit.

Best practices summary

1. Always backup before major operations 2. Use version control for configurations 3. Document entries separately 4. Monitor file changes if resets occur 5. Verify permissions are correct 6. Exclude from Time Machine if needed 7. Use hosts file manager with auto-backup 8. Test restoration process regularly

Conclusion

Hosts file changes disappearing after reboot is frustrating, but preventable. The most common causes are macOS updates, Time Machine restorations, security software, or daemon overwrites. By implementing a robust backup strategy and understanding what can reset your file, you can ensure your configurations persist.

Remember: Backup regularly, document your entries, and monitor for unexpected changes. With these practices, you'll never lose your hosts file configuration again.

For the easiest experience with automatic backups, version history, and easy restoration, consider using Locahl (€9.99). It handles all the complexity of hosts file management, ensuring your changes are always safe and easily recoverable.

If you're experiencing persistent issues, check our hosts file troubleshooting guide or learn about fixing permission issues that might be related.