@kichikawa_2913 we've reviewed this a bit more as a team, and believe that there are a few things to consider here.
At first, it's clear you have a large, "older" Active Directory. There is a tremendous amount of customization one can do to Active Directory, and do enough of them over the years, and you end up with a "older" directory that has layer of layer of compatibility shims. You should see the crazy hacks they had to implement to get MSA accounts working...
It's important to note here is the fact that Microsoft Active Directory and .NET (Core) do not play nicely together. It took Microsoft over 10 years to get .NET Framework to work with Active Directory, and it's still really quirky. We've worked-around as many of the bugs as we can.
Microsoft is still trying to get .NET Core on Linux to work properly with Active Directory, but it's got a very long way to go as you're seeing. There are so many strange behaviors we've already had to work-around (like methods sometimes returning strings, sometimes returning byte arrays) -- and these behaviors will just come with new versions of their library.
For all we know, the crazy "2 or so minutes" to do a login query could be a parsing error in their library? Or something timing out in their network code, but not logging an error? We saw all that in .NET Framework. In any case, we can only guess because their library provides no diagnostic information for us to use.
At this point, you should open a support ticket to Microsoft. This is the only way we can see how to identify why you have a "2 minute or so" delay to run a basic login query.
The code we have is really, really simple. It follows all of Microsoft's guidelines, and it'd be super-simple for you to reproduce the exact problems for them to show them. They have some advanced monitoring tools that can detect exactly what crazy stuff is happening between the query and Active Directory.
We can't do this, because we don't have access to your directory. It's unique to your setup and
configuration, somehow.
Alternatively, just use Windows instead. It will be significantly cheaper in the long-run (I suspect we've already burned through a lifetime's worth of licensing fees diagnosing this problem). Microsoft is still years away from even having the support infrastructure to help their customers with Linux problems, so any time there's a slight problem on Microsoft's end (SQL Server, .NET Core) , it will be "DIY" -- which really means, spend a lot of your time fixing quirks on their software.
