PHP Sessions across sub domains

Question

I am trying to set up the following:

auth.example.com
sub1.example.com
sub2.example.com

If the user visits sub1.example.com or

Answer 1

Sub domain and root domain Cookie Sessions Combined Use

Resource: http://php.net//manual/tr/function.session-set-cookie-params.php

I've tested works

sub.example.com/sessionadd.php?id=123

example.com/sessionview.php // 123

-- Codes