One of the situations that you may end up at is changing your SharePoint servers domains. For instance, your SharePoint servers joined the domain "contoso.com", you built your SharePoint farm and it's operational now. Later, due to a business need, you would like to disjoin the servers from this domain and let them join another domain "ahmedamin.com". Will your SharePoint farm be functional then? What's the impact?
As you know, SharePoint has many domain service accounts that run either SharePoint services, or web applications. Hence, if the SharePoint servers disjoin the domain, these service accounts won't be able to contact their domain; hence, they will not be able to run their services. As a result, your SharePoint farm will be totally down!
So, the first thought that has just come now into your mind is to change the SharePoint service accounts and to use new service accounts in the new domain. Is this possible (supported)?
Unfortunately, this is not supported! Although this looks technically possible and there are plenty of blogs talking about how to do so, but we don’t support domain name changes with SharePoint, even in such circumstance (i.e. customer wants to rename root domain, this will have an impact on child domain’s FQDN but not on its NetBIOS name).
Hence, the solution here is to setup a new farm in the new domain and restore/attach your data, which is the safest and recommended way to do so.