We have already discussed about Nagios server and client installation and configurations, If you may get an error on Host Status,

"check_ping: %s  Warning threshold must be integer or percentage! in Nagios"



Open your clinet server cfg file in  Nagios server and ensure below check_ping,
  



define service{

   use                       generic-service

   host_name                 host..yourhostname.com

   service_description       Host Status

   normal_check_interval     5

   check_command             check_ping!200.0,20%!400.0,90%

}