I regularly have to test internal systems by adding an entry to the hosts file on my computer. As I keep quite a few tabs open this can cause issues when I need to use the original host system to do some work as I do not want to close all of my tabs to restart Chrome. And when I finish my testing and remove the entry from the hosts file, I need to restart the browser to make sure that I do not have the test DNS entry for my host.

IF you place the following in the address bar:

chrome://net-internals/#dns

You will get a page for DNS that has the following button:

This will clear the browser DNS cache and you can use the list below to see the current state of DNS entries below to verify your DNS is as expected.

To install PostgreSQL in ubuntu

Add the repo for postgres to the apt repo list:

 sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" >> /etc/apt/sources.list.d/pgdg.list'
 sudo wget -q https://www.postgresql.org/media/keys/ACCC4CF8.asc -O - | sudo apt-key add -

To install the postgres database packages:

 sudo apt-get update
 sudo apt-get install postgresql postgresql-contrib