Our system: 1 AD, Exchange 2010 CAS array sp1(cas2010) and exchange 2007 sp2 (cas2007), to save cost, currently we only use SRV DNS record for exchange 2007 autodiscover and it's working: for IPAD/Iphone and Outlook anywhere. Now I plan to move some users to Ex2010 servers, can I just use the same SRV DNS record (which is cas2007.domain) for both Exchange 2010 users and exchange 2007 users? if I buy autodiscover.domain SSL certificate for cas2010, it will be good for 2007 users too? becuase the domain is the same, I see I must share one record for autodiscover, being SRV record or autodiscover.domain. Which is better between a CAS2007 server or CAS2010 server as the autodiscover endpoint? we have no plan to get rid of EX2007 for long time, so I guess I need both certificates even the autodiscover only has one entry point to outside devices. Thanks for any suggestions.