problem with create exchange account on outlook

i have exchange server 2010

there is no problem with create and modify  new mail boxes or send, recieved emails

and outlook web app work.

but when i need to add mailbox to outlook 2010 or any outlook version i have this error

"the name cannot be resolved. the connection to microsoft exchange is unavailable. outlook must be online or connected to complete this action"

or  this error "the connection to microsoft exchange is unavailable, outlook must be online or connected to complete this action"

all network connection were tested and there is no firewall or antivirus block this operation