Update DNS faster!
Updating and refreshing the layers of DNS caching
Your ISP cache if you set your desktop to auto lookup DNS, it then defaults to your router or ISP DNS cache. It could be a whole day old! Drop it and tell your desktop to use Google DNS instead.
If your Desktop DNS still doesn't update - in Windows the default DNS cache update time is over 20 min... why wait?
Flushing your cache on Windows
Open command prompt and use this command; ipconfig /flushdns VOILA! Cleared!
Flushing your cache on Mac OS X
The commands to flush cache in OS X are slightly different depending on the version you're running. First, make sure you've opened up your terminal on your computer.
Once opened, run the command below that corresponds to your version of OS X.
OS X 12 (Sierra) and later
macbook$ sudo killall -HUP mDNSResponder;sudo killall mDNSResponderHelper;sudo dscacheutil -flushcache
OS X 11 (El Capitan) and OS X 12 (Sierra)
macbook$ sudo killall -HUP mDNSResponder
OS X 10.10 (Yosemite)
macbook$ sudo dscacheutil -flushcache;sudo killall -HUP mDNSResponder
Versions 10.10.1, 10.10.2, 10.10.3
macbook$ sudo discoveryutil udnsflushcaches
Ok now your Browser!!! Now that the world, your ISP, your desktop are in sync... Why is my site STILL not coming up!!! Well... good old browser cache that once loaded the same site files elsewhere (old IP address) still may thinks its there. Delete entire browser cache or use another browser you normally don't use as a test.