Moving to Office 365 / rename domain / hybrid vs cutover

Question

I have a domain with approximately 35 users running Windows 2008R2 server and Exchange 2010.
lets say the name is domain1.com

However at some point sometime ago company name changed and as such emails changed, so while is AD is still domain1.com the emails are domain2.com

We no longer own domain1.com domain so for our purposes its a local domain, we only own domain2.com
Exchange is setup to receive emails via "Accepted domains" and all users have proxy email address user@domain2.com setup as Primary SMTP email.

We are preparing to migrate to Office 365 and considering a hybrid environment, although cutover may work as well.

All literature i am reading is that a recommendation for on-prem AD to be same as Azure AD, i.e. domain2.com however reading about renaming domains it sounds like it's a nightmare to deal with.

Can you pls give me step by step recommendations? Am i overcomplicating? Should i just keep my local domain as domain1.com and Azure domain2.com?
Should i create a brand new local domain2.com and migrate users from domain1.com to domain2.com?

Also am i better off to keep a hybrid vs cutover environment? It sounds like there is a benefit in hybrid but i also don't want to overcomplicate things as well.

thank you so much for your help in advance.

Answer 1

Hello @Maksim Kurpichau ，

Thank you for posting here.

To better understand our question, please configm the following information:

1. What does domain1 do?
2. Does domain2 only have email function?
3. Where are DC servers, Exchange server and approximately 35 users in (domain1 or domain2) now?
4. For moving to Office 365, does "cutover" mean you do not want to keep on-premise domain, but you only keep Azure domain?
5. For hybrid environment, do you mean all DC servers, Exchange server and approximately 35 users are in domain1, but email is in domain2? If so, does it work for you?
6. Are the domain1 and domain2 have trust relationship (such as two-way forest trust)?

Meanwhile, I am not sure why you want to rename domain, based on my knowledge: the domain rename operation is not supported in Microsoft Exchange 2000 server,Microsoft Exchange Server 2007 or Exchange Server 2010,Microsoft Exchange Server 2013.

If anything is unclear, please feel free to let us know.

Best Regards,
Daisy Zhou

Answer 2

Hi Daisy, thank you so much for your response, pls see answers below:

1. domain1 is a local on-prem AD domain.
2. domain2 is only used for emails
3. DC controller, Exchange server and 35 users are in domain1 currently.
4. We still want to keep our local domain, however we probably won't need old Exchange 2010? we don't mind keeping it just don't see why we want to have it.
5. So this is what confuses me. I read that preferrably on-prem domain name should be same as Azure domain name and local domain should have same fqdn as email. As we also want to make sure users can sign in using user@domain2.com into PCs and Office 365. Currently users sign into local PCs as domain1\user
6. I haven't created any trust relationship yet between domain1 and domain2 yet. Currently the only purpose of domain2 is "accepted domain" in Exchange transport and proxy email address on user accounts

i am reading same, that renaming domain is a bad idea. Why i think about renaming is because i want to make sure users can sign everywhere using user@domain2.com since name of domain1 is really no longer an fqdn and i am concerned since domain1 will be local and domain2 will be on Azure there will be some kind of issues with configuration

I hope it's not too confusing and makes sense.

Answer 3

Hello @Maksim Kurpichau ,

Thank you so much for your clarify.

1.Is domain2 a local domain or Azure domain?
2.Do you have Exchange server in domain2?

I mainly focus on the questions/issues about on-premise AD domain and I don’t know much about Azure domain and Exchange server.
I suggest we put all the resources (DCs, Exchange server, domain-PCs and domain users and so on) in the same domain.

Best Regards,
Daisy Zhou