Sanjiv Singh thinks this is interesting: only offer three states From 1. Introducing Nagios from Learning Nagios 4 by Wojciech Kocjan Publisher: Packt Publishing Released: March 2014 Note  Warning  Critical  Unknown Share this highlight http://www.safaribooksonline.com/a/learning-nagios-4/47983/ Twitter Facebook Google Plus Email Get Instant Access Now Start a Free Trial Learn about Safari for Business Have an account? Sign in. Minimise Unlock the rest of Learning Nagios 4 and 30,000 other books and videos By clicking this box, you confirm that you have read and agree to the terms and conditions of our Membership Agreement, and you understand that when your trial period ends, you will be required to provide billing information if you wish to continue using the service. Unlock the rest of this book Start a Free 10-Day Trial loading Learn about Safari for Business Have an account? Sign in.