CodewrightConsequence-aware terminal workflows

Flush the local DNS cache

Low risk
What do risk levels mean?
Read-only
Inspects state without changing anything.
Low risk
Reversible with a routine follow-up command.
Medium risk
Changes state; undo path documented.
Destructive
Deletes or overwrites; confirmation required.

Clears the operating system's DNS resolver cache so stale records are discarded and the next lookup fetches fresh answers, typically after a DNS change or when a site resolves to an outdated address.

networkdnscacheflush

Commands

Clear the directory services DNS cache

sudo dscacheutil -flushcache

Signal the resolver daemon to drop its in-memory cache

sudo killall -HUP mDNSResponder

Verification

nslookup example.com

The name resolves normally, confirming the resolver is healthy after the flush.

Undo

Not undoable

The cache cannot be restored, and does not need to be — it repopulates automatically as names are resolved.

Pitfalls

  • The Linux command requires systemd-resolved; distributions using dnsmasq or nscd need "sudo systemctl restart dnsmasq" or "sudo systemctl restart nscd" instead.
  • Browsers keep their own DNS caches, so a stale result inside a browser may also need a browser restart or its internal DNS cache cleared.

Related