Site is offline Try Again Later

Genarally,we all know about offline - not connected to INTERNET.Here i found an unusual message while i am trying to visit the site myunit.sodexonet.com  as
"Site is offline.Try again later".

Then i checked whether the site is up or down and i found that it is up.Then i doubted why such an message.If the site's status is offline then it is said to be down.But i dont know why such an message even if the site is found to be up.

Below is the proof for this error message,