Hosts File Not Working After Edit on Mac: Complete Fix Guide

You've edited your hosts file, added the entries correctly, but nothing seems to work. The domain still resolves to the old IP address, or worse, doesn't resolve at all. This frustrating situation is more common than you think, and the good news is that it's almost always fixable.

In this comprehensive troubleshooting guide, we'll walk through every possible reason why your hosts file changes aren't taking effect on macOS, and provide step-by-step solutions for each issue.

Understanding how the hosts file works

Before diving into troubleshooting, it's essential to understand the DNS resolution hierarchy on macOS. When your Mac tries to resolve a domain name, it checks in this order:

1. Hosts file (/etc/hosts) - checked first 2. DNS cache - macOS caches previous DNS lookups 3. DNS servers - configured via Network settings or DHCP

If your hosts file entry isn't working, something in this chain is likely interfering. Let's identify and fix each potential issue.

Issue #1: DNS cache not flushed (most common)

This is by far the most common reason hosts file changes don't work. macOS aggressively caches DNS lookups to improve performance, but this means your hosts file changes won't take effect until the cache is cleared.

Why DNS cache matters

When you first visit a domain, macOS stores the resolved IP address in its DNS cache. Subsequent requests use this cached value instead of checking the hosts file again. This is why your changes seem to be ignored.

Solution: Flush DNS cache

For macOS Sierra and later:

sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

For macOS versions before Sierra:

sudo killall -HUP mDNSResponder

For macOS Big Sur and later (additional step):

sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder
sudo killall mDNSResponderHelper

Verify DNS cache flush

After running the command, verify it worked:

ping yourdomain.local

You should see it resolving to the IP address specified in your hosts file.

Issue #2: Browser DNS cache

Even after flushing system DNS cache, browsers maintain their own separate DNS cache. This is why your hosts file might work in Terminal (ping, curl) but not in your browser.

Chrome/Chromium browsers

1. Open chrome://net-internals/#dns in the address bar 2. Click "Clear host cache" 3. Close and restart Chrome completely

Alternatively, restart Chrome with cache disabled:

/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --dns-prefetch-disable

Firefox

1. Open about:networking#dns in the address bar 2. Click "Clear DNS Cache" 3. Restart Firefox

Safari

Safari uses the system DNS cache, so flushing system DNS should be sufficient. However, if issues persist:

1. Safari menu > Preferences > Advanced 2. Check "Show Develop menu" 3. Develop menu > Empty Caches 4. Restart Safari

Edge and other Chromium browsers

Follow the same steps as Chrome, using edge://net-internals/#dns for Edge.

Issue #3: File permissions

Incorrect file permissions can cause macOS to ignore the hosts file entirely. The hosts file must have specific ownership and permissions to function correctly.

Check current permissions

ls -la /etc/hosts

You should see something like:

-rw-r--r--  1 root  wheel  1234 Feb  6 10:30 /etc/hosts

Correct permissions

• Owner: root
• Group: wheel
• Permissions: 644 (rw-r--r--)

Fix permissions

If permissions are incorrect:

sudo chmod 644 /etc/hosts
sudo chown root:wheel /etc/hosts

Verify permissions fix

After fixing permissions, flush DNS cache again and test:

sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder
ping yourdomain.local

Issue #4: Syntax errors

Even a small syntax error can prevent the entire hosts file from working correctly. macOS is strict about hosts file format.

Correct format

Each entry must follow this exact format:

IP_ADDRESS    DOMAIN_NAME

• Use a single tab or multiple spaces between IP and domain
• Each entry on a single line
• No trailing spaces
• Comments start with #

Common syntax mistakes

Wrong: Multiple domains on one line

# ❌ Wrong
127.0.0.1    domain1.com domain2.com

Correct: One domain per line

# ✅ Correct
127.0.0.1    domain1.com
127.0.0.1    domain2.com

Wrong: Missing separator

# ❌ Wrong
127.0.0.1domain.com

Correct: Tab or spaces

# ✅ Correct
127.0.0.1    domain.com

Wrong: Extra spaces

# ❌ Wrong
127.0.0.1     domain.com   

Correct: Clean format

# ✅ Correct
127.0.0.1    domain.com

Validate syntax

Check your hosts file for syntax errors:

cat /etc/hosts | grep -v "^#" | grep -v "^$" | awk '{print $1, $2}'

This shows all active entries. Each line should have exactly two fields: IP and domain.

Issue #5: File encoding problems

The hosts file must be in UTF-8 encoding without BOM (Byte Order Mark). Some text editors save files with incorrect encoding, which can cause macOS to ignore entries.

Check encoding

file /etc/hosts

Should show: ASCII text or UTF-8 Unicode text

Fix encoding issues

If encoding is wrong, recreate the file:

# Backup first
sudo cp /etc/hosts /etc/hosts.backup

# Edit and save as UTF-8 without BOM
sudo nano /etc/hosts

When saving in nano, ensure you're not adding any special characters. For GUI editors, check encoding settings before saving.

Issue #6: System Integrity Protection (SIP)

While SIP shouldn't prevent hosts file edits, it can interfere in rare cases. SIP protects system files, but the hosts file is designed to be editable.

Check SIP status

csrutil status

If SIP is enabled (normal), it shouldn't affect hosts file functionality. Only disable SIP if absolutely necessary and you understand the security implications.

Issue #7: Network location or VPN interference

Sometimes network configurations or VPNs can override hosts file entries by using their own DNS servers.

Check active DNS servers

scutil --dns | grep nameserver

VPN DNS override

If you're using a VPN, it might be routing DNS queries through VPN servers, bypassing the hosts file. Try:

1. Disconnect VPN temporarily 2. Flush DNS cache 3. Test hosts file entries 4. If it works, configure VPN to use local DNS

Network location

macOS Network Locations can have different DNS settings:

1. Apple menu > System Preferences > Network 2. Location dropdown (if multiple locations exist) 3. Check DNS settings for each location

Issue #8: IPv6 vs IPv4 conflicts

If you're only adding IPv4 entries but your system prefers IPv6, resolution might fail or use the wrong address.

Add IPv6 entries

For localhost entries, include both IPv4 and IPv6:

127.0.0.1       yourdomain.local
::1             yourdomain.local

Disable IPv6 (if needed)

If you want to force IPv4 only:

networksetup -setv6off Wi-Fi
networksetup -setv6off Ethernet

Re-enable with:

networksetup -setv6automatic Wi-Fi
networksetup -setv6automatic Ethernet

Issue #9: mDNSResponder not responding

The mDNSResponder daemon handles DNS resolution on macOS. If it's not working correctly, hosts file changes won't take effect.

Restart mDNSResponder

sudo killall mDNSResponder
sudo killall mDNSResponderHelper

The system will automatically restart these services.

Check mDNSResponder status

ps aux | grep mDNSResponder

You should see the process running.

Complete troubleshooting checklist

Follow this checklist in order:

1. ✅ Verify hosts file syntax - Check for errors 2. ✅ Check file permissions - Should be 644, owned by root:wheel 3. ✅ Flush DNS cache - Run the flush command for your macOS version 4. ✅ Restart browser - Close completely and reopen 5. ✅ Clear browser DNS cache - Use browser-specific methods 6. ✅ Test with Terminal - Use ping or curl to verify 7. ✅ Check for VPN interference - Disconnect VPN if active 8. ✅ Verify encoding - Ensure UTF-8 without BOM 9. ✅ Restart mDNSResponder - If all else fails 10. ✅ Check network location - Verify DNS settings

Testing your hosts file

After applying fixes, test systematically:

Step 1: Terminal test

ping -c 3 yourdomain.local

Should show your hosts file IP address.

Step 2: DNS lookup test

dscacheutil -q host -a name yourdomain.local

Should return your hosts file IP.

Step 3: Browser test

1. Clear browser cache completely 2. Open in incognito/private mode 3. Navigate to your domain 4. Check browser developer tools Network tab for resolved IP

Step 4: curl test

curl -v http://yourdomain.local

Check the resolved IP address in the output.

Prevention: Best practices

To avoid hosts file issues in the future:

Use a GUI tool

GUI applications like Locahl automatically handle:

• Syntax validation
• Permission management
• DNS cache flushing
• Backup creation
• Encoding verification

Regular backups

Always backup before editing:

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

Test incrementally

Add one entry at a time and test immediately. This makes it easier to identify problematic entries.

Document entries

Use comments to document your entries:

# Local development - Project Alpha
127.0.0.1    alpha.local
127.0.0.1    api.alpha.local

# Local development - Project Beta
127.0.0.1    beta.local

Advanced: Debugging DNS resolution

For persistent issues, enable detailed DNS logging:

sudo log config --subsystem com.apple.network.dns --mode level:debug

Then check logs:

log show --predicate 'subsystem == "com.apple.network.dns"' --last 5m

This shows exactly how macOS is resolving domains.

When to seek help

If you've tried all troubleshooting steps and hosts file still isn't working:

1. Check system logs - Look for DNS-related errors 2. Try safe mode - Boot into safe mode and test 3. Check for conflicting software - VPNs, firewalls, security software 4. Verify macOS version - Some older versions have known DNS issues

Conclusion

Hosts file not working after editing is frustrating, but it's almost always fixable. The most common issues are DNS cache not being flushed and browser DNS cache. By following this guide systematically, you should be able to identify and resolve the problem.

Remember: flush DNS cache, restart browser, check syntax, verify permissions. These four steps solve 90% of hosts file issues.

For a hassle-free experience managing your hosts file with automatic validation, DNS flushing, and backup management, consider using Locahl. At just €9.99, it eliminates the common pitfalls that cause hosts file problems and saves you time troubleshooting.

Ready to streamline your local development workflow? Learn more about editing hosts file on Mac or check out our complete hosts file guide for advanced techniques.