Open SM and cruise down to your Servers tab, it'll give you all the details in the right window.
Was it working and suddenly stopped? or are you having trouble getting it to work at all?
If it was working and now stopped, have you done anything to your network? Changed ISP's? Added/changed firewalls?
If not, check that you're pointing to the proper DNS server from your Exchange server.
I'm Certifiable, not certified.
It just means my answers are from experience, not a book.