Hi There, Yep, I have had this issue to.. after further testing what I found was a limitation in access. To verify theis I went back a level and endured that the ISA could access \\ip address\Exchange once this worked it then stopped the error 500... my issue was a reverse Pix NAT.. i had Nat'd A to B and expected it to work........ Nope by then Natin B to A .........................voila.. good luck and remeber that ISA is just a Pix but with an insecure OS to support to.. "nobody" wrote: > I have setup a cluster. I enabled a mailbox and can browse and logon to it > via owa directly to the exchange virtual server ip address. I however cannot > browse to it via the dns name. > > Also When I try to log in via the front end, I get HTTP 500 Internal Server > Error. > > any ideas? > > >