sudo killall -HUP mDNSResponder: Clear DNS Cache on Mac

delete dns cache mac refers to clearing the local DNS resolver cache on macOS using Terminal commands dscacheutil and killall to force fresh DNS lookups.

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

This two‑command sequence flushes both the Directory Services cache and the mDNSResponder daemon cache. Run it when DNS changes (hosting migration, record updates) do not reflect after propagation.

When to flush the DNS cache

Stale cache causes site unreachable errors, outdated content, or misdirected traffic. Typical triggers:

• After changing a domain’s A/AAAA records
• After switching hosting providers
• After reconnecting a VPN that changes nameservers
• When a site that worked earlier now shows “server not found”

How to flush DNS cache on any modern macOS

1. Open Terminal from Applications → Utilities.
2. Execute the following command and enter your admin password when prompted:

   sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

   No output signals success.

3. Optional: verify with dig example.com +short to confirm the old IP is gone.

Common errors

• “Operation not permitted” – Ensure you use sudo and have admin privileges. Run sudo -v to refresh credentials.
• “No matching processes” – mDNSResponder is not running. Restart it: sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist.
• “dscacheutil: invalid option” – The -flushcache flag requires macOS 10.7+. On older systems (10.5/10.6) use sudo lookupd -flushcache.
• Password not accepted – Verify your password or check sudoers restrictions.
• Still seeing old IP after flush – The TTL may not have expired globally, or a secondary cache (browser, router) persists. Clear browser cache and check DNS propagation.
• System feels slower after flush – Temporary; performance returns as new entries populate.

Version history

The sudo killall -HUP mDNSResponder command works on macOS 10.9 and later. On macOS 10.10 and earlier, some guides mention sudo discoveryutil mdnsflushcache, but that is deprecated. The command above is universal for modern releases (macOS 10.11+, including macOS Ventura, Sonoma, Sequoia).

sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

sudo killall -HUP mDNSResponder

sudo dscacheutil -flushcache

# macOS 10.12+ (including Sonoma, Sequoia)
sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder

sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder