After Changing the hosts File

I edited the hosts file at /etc/hosts , do I need to restart the service for my changes to take effect?

No, it's not necessary. You don't even need to restart the browser. The effects should take place as soon as you refresh or load a web page.

On each DNS request the hosts file is read. This means it is not saved to memory, so the changes you make are in real time.   Your machine checks the hosts file first. If a mapping is not found for a hostname, then it asks your DNS server.

How to Exit vi

Press escape to get into command mode if you re not already in command mode (i.e. if you are in insert/edit mode) .. Even if you are not in the edit mode press escape any way, it s OK. 

So, press esc, then

type one of these:

:q to quit and dont save
:q! to quit with out saving changes or prompts (if you have made changes)
:w to save
:wq to save and quit 


:x to save and quit 


emacs - ^X^S to save, ^X^C to quit
esc shift^ZZ to save and exit.


Notes:

Adding an exclamation mark at the end of the command means "do it!" - as in  :q!

When you will press escape the "insert" mode will be disabled, then you need to type : After that you can provide q! or w or wq and hit enter.