I planning to Migrate exchange 2007 to 2013 with coexistence. I am thinking about buying new certificate for new exchange 2013 and also create zone for public DNS domain, as required by new certificate.
The old certificate applied on exchange works for domain.local and valid for couple of months. I would like to leave it running and migrate non-critical mailboxes first and test their access and gradually move high profile users with big mailboxes.
Would there be any issues with existing certificate activesyc, autodiscover or owa, if I create zone for public DNS? Or it will continue to work without any issue.
Also, i have spam filtering solution from securence and MX on DNS point to securence mail server and securence has IP address of mailserver. How to I approach about creating legacy DNS entry for co-existence? Do I create that in DNS or in securence?