DNS cache on your local computer stores IP addresses of hostnames you have recently visited. From time to time IP address changes. You might wait a couple of hours until your DNS cache refresh automatically or clear the DNS cache manually with the following commands.
Clearing DNS is very simple. Find a ‘Command Prompt’ in your start menu. Right click and select ‘Run as Administrator’. Then type the following command:
Clearing DNS is very simple. Open a Terminal and type the following command. You will be asked for administrator password afterwards.
killall -HUP mDNSResponder