Clearing Flushing / DNS cache

This procedure is necessary in order for previously cached resolutions to be cleared out and subsequent lookup to be performed based on newly configured DNS settings.

What is DNS cache?

DNS servers are used to convert domain names such as into numerical addresses that can be processed by computer systems. Operating systems attach their own cache known as DNS cache. These DNS caches save all relevant info for name resolution. Within the TTL, queries are answered directly from the cache.

Each DNS cache has an entry known as TTL (time to live) where data remains valid for a given time.


  1. Open and Run Command Prompt as Admin
  2. Run this command: ipconfig /flushdns


  1. Open Terminal
  2. Run this command: lookupd -flushcache

OS X 10.5 and 10.6 LEOPARD

  1. Open Terminal
  2. Run this command: dscacheutil -flushcache

OS X 10.7 and 10.8 Lion

  1. Open Terminal
  2. Run this command: sudo killall -HUP mDNSResponder

OS X 10.9 and 10.10.4 Yosemite, 10.11 El Capitan and 10.12 Sierra

  1. Open Terminal
  2. Run these commands:
    • sudo dscacheutil -flushcache
    • sudo killall -HUP mDNSResponder

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