The Oakland Symphony Chorus has run a DNN site for some years, currently at version 6.8.2,  The domain is http://www.oaklandsymphonychorus.org.  Four years ago we merged with our local symphony and youth orchestra into a single larger arts group, dba Oakland East Bay Symphony; and the new organization is building a single site for all 3 divisions, based on WordPress.  The Chorus will have its own landing page (and other pages) on the new site, and the executive director wants the domain oaklandsymphonychorus.org to resolve to the new chorus landing page.

I assumed that we'd simply shut down the DNN site.  But he told me tonight that he wants to keep the login-protected "member only" pages on the DNN site, at least for a month or two while his contractors figure out how to make WordPress do that.  

It appears that my best option is to get a new domain name for the old site, and direct member traffic from the new site to the login page on the new domain.  Other than changing the PortalAlias table (and the Internet DNS of course), is there anything else I need to do?  In particular do I need to get a new SSL certificate for the new domain name??   We just renewed the SSL certificate for the current domain name last month.  

Advice on making this go smoothly would be much appreciated, in particular the timing issues of when to change things.  Would I start the DNS changes to the new domain name, and then change PortalAlias?  Are there other settings I need to change in either Host or Admin?  (Yes, I'll go look; this just got thrown at me...)

We are now in our performance season with rehearsals every week, and the "member only" pages are used for communication with singers.

Thanks for confirming my suspicions that the SSL certificate is bound to the domain name.  But I must not have made myself clear:  http://www.oaklandsymphonychorus.org will redirect to the new site and refer to a specific subpage.  That's why we're looking at changing the domain name of the old site and getting a new cert, so we can still navigate to the login page and get SSL access to the old member pages.  SSL is currently enabled for all the member pages.

I apologize for not getting back on this sooner; my desktop crashed for the 4th time in 5 years and I'm having a new one built...

I have two questions about directing HTTPS and HTTP separately:

What do we have to do to the DNS for this?  Do we have to use a CNAME or what?

You say "all DNN pages" have to be marked for SSL.  Does this include pages which still exist on the site but aren't accessible from the public menu?  We have some accumulated pages that are not actually marked SSL but can only be reached from the Pages list (which itself requires SSL).  Do we have to specifically change those to SSL or can we leave them as they are?