hi Kjell,
CRM does support RO DC's however if you need to write to AD e.g. creating users, then wouldn't work.
For option 2 to work, what you need to do is to work with AD sites and services, you need to make sure CRM is hosted in a SITE that contains a number of DC's for redundancy. CRM finds the DC's querying DNS for SRV (DCs) records on their SITE first. If you
have SRV records on the site, DNS will return those and here you get CRM working with those DC's first.
I have blogged not specifically about this on the below post but here is a post which may help:
http://quantusdynamics.blogspot.co.uk/2011/12/crm-40-ifd-dmz-secure-deployment.html
Visit my blog for CRM material, improving performance, kerberos, IFD, development tips, etc. :) http://quantusdynamics.blogspot.com
