Joining Windows domain requires 2 different steps:
- the very first time your workstation or server joins the domain
- once you have successfully join target domain, you can authenticate against this domain and connect to it.
As explained by Microsoft, first step does require to use local Admin account
[quote]To join a computer to a domain, you must be logged on to the computer
with the local Administrator account or, if you are logged on to the
computer with a user account that does not have local computer
administrative credentials, you must provide the credentials for the
local Administrator account during the process of joining the computer
to the domain. In addition, you must have a user account in the domain
to which you want to join the computer. During the process of joining
the computer to the domain, you will be prompted for your domain account
credentials (user name and password).[/quote]
Based on this, what do you mean when you say that it requires admin account?
- admin account to join first time
- your domain account to open session on this server must be also “domain account”?