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Wilcard and Self-Signed Certificates - Exchange 2010 upgrade

We already own certificates and more importantly a wildcard certificate for our domain.  During the upgrade to Exchange 2010 from Exchange 2003, we need to make sure that we can use the wildcard to minimize downtime.  If we were to request new certificates, we would have to revoke the current certificates meaning we'd have untrusted connections for end-users until we get the new certificate generated.

If we use a wildcard certificate on our externally facing Load Balancers and do self signed certificates internally, will this work for Exchange 2010 and 2003 during coexistence?  I seem to think it will since the wildcard is a catch-all and will work for the new legacy.domain.com and the older mail.domain.com along with autodiscover.domain.com.

Can we do this?
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Glen Knight
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We have F5 Load Balancers to work with.  I'm not sure of the model, though, but it's a pretty sweet box.  I'm just now getting a good handle on what it is capable of from the subject matter expert on the team here.
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What kind of exchange setup do you have? one server for each role?
The 2003 setup is 2 front-end OWA boxes, 1 Transport Box, and 3 Mailbox servers.  

We're looking at 2 CAS/HUB (Dual role) and 3 Mailbox servers for the 2010 setup.  We're also debating SSL offloading at the F5s to help with CPU load on the front-end servers.  No UM or Edge in the setup as we already have hardware SPAM and Anti-Virus boxes.

We're really hesitant though with such a large user-base.  Once we start the upgrade, we want to make sure that it's as seamless as possible.
Whatever you do you will need to have the CAS and the Front End servers available externally at the same time.  Exchange 2010 will redirect the clients to the legacy URL so this will also need to be created.  You should really just use a CAS Array and point the clients at this, there is no need to use a load balancer since the CAS array uses NLB
We're staying away from the software LB solution since the old front-end is already Load Balanced through the same hardware.  By creating a new VIP, we're hoping that it will redirect almost instantly with the new external DNS change.  Here's the hardware load balancing article that I've been reading for Exchange 2010:  http://goo.gl/kDNNF  
OK, that's fine.  You will still require the legacyURL and an additional IP address.

And as already stated, you can just import the wildcard certificate so there is no need to use self signed certs.
Thanks for the good feedback!  I have yet to find anyone who's had anything "break" during the upgrade to 2010, but we still have to be cautious.
I have done quite a few in my time and documented them in articles both here on EE and on my blog, if you do them carefully and allow appropriate amounts of time there is no reason why anything should go wrong.