My 4 node DAG spread across two AD sites.
2 in Primary and other 2 in Secondary site.
We also have 2 CAS in Primary and other 2 in Secondary (Netscaler VIP in each site with different DNS name).
This blog says DNS IP change from Primary CAS to Secondary is "recommended" or "guide line". Not definitely a "requirement" if I've read correctly. It's reasonable because Primary CAS is totally down, no one can tell Outlook the new CAS name in Secondary site.
"changing the primary datacenter's DNS records to point to the IP addresses in the secondary datacenter, that is still our recommendation"
However this blog guy succeeded to perform the event WITHOUT changing DNS record.
It seems Outlook retrieves the new CAS name from AD without relying on primary CAS name.
I'd like to understand :
- It looks DNS change is not "requirement". Why MS guy still keep this procedure as "recommendation"?
- What happen if we don't follow MS guidance?
- What is the technical query processes that Outlook to get CAS name. Where's the attribute that Outlook determine the new CAS name in new site?
Cross site failover is an event in very extreme situation and we most probably can't expect DNS team guy to be available timely. It's much better if we can just rely on AD replication.
Not sure why the guidance keep this process manual.