Command Prompt Flush DNS: ipconfig, PowerShell, and DNS Client Service

Q: Is there a registry setting for DNS cache size?

Yes - `HKLM\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters\MaxCacheEntryTtlLimit`. Default 1 day.

Command prompt flush DNS on Windows: ipconfig /flushdns in cmd or PowerShell. Clears the local DNS Resolver Cache. The team that runs this after DNS record changes has fresh resolution without waiting for TTL.

The ipconfig /flushdns command
PowerShell equivalent
When DNS Client service is stopped
Other useful ipconfig commands
Verify the flush
Display DNS cache before flush
For IT admins: flush on multiple machines
FAQ

The ipconfig /flushdns command

Open Command Prompt (Admin):

ipconfig /flushdns

Output: Successfully flushed the DNS Resolver Cache.

The team that runs this on Windows has fresh DNS.

PowerShell equivalent

Open PowerShell:

Clear-DnsClientCache

Same effect, different syntax. The team that uses PowerShell has the modern way.

When DNS Client service is stopped

If the DNS Client service is stopped, ipconfig /flushdns fails with The requested service has not been started. Fix:

net start "DNS Client"

Or via Services GUI: services.msc -> DNS Client -> Start. The team that has the service stopped has the fix.

Other useful ipconfig commands

ipconfig /all            # full network config
ipconfig /displaydns     # show DNS cache
ipconfig /release        # release DHCP lease
ipconfig /renew          # renew DHCP lease
ipconfig /registerdns    # manually register DNS

The team that uses these has full network debugging.

Verify the flush

After flushing:

nslookup example.com

Should show the new IP. The team that verifies has confirmation.

Display DNS cache before flush

ipconfig /displaydns

Shows cached entries with their TTLs. The team that uses this sees what’s about to be flushed.

For IT admins: flush on multiple machines

Use PsExec or PowerShell remoting:

Invoke-Command -ComputerName server1,server2,server3 -ScriptBlock {
  Clear-DnsClientCache
}

The team that flushes on multiple machines has consistent state.

FAQ

Does ipconfig /flushdns require admin?

Yes - it modifies the system DNS cache. Run as Administrator.

How long does the DNS cache take to refill?

As you make DNS queries. The team that flushes and re-browses repopulates the cache.

Is there a registry setting for DNS cache size?

Yes - HKLM\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters\MaxCacheEntryTtlLimit. Default 1 day.

Can I flush DNS on a remote machine?

Yes via PowerShell remoting or PsExec. The team that has admin access can flush remotely.

Does ipconfig /flushdns affect other users?

Yes - the DNS Client service is system-wide. The team that flushes on a server affects all users on that server.

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