I’m a sysadmin/consultant by trade. I cut my teeth on IPv4 addressing way back in the NT4 days when most addressing was still class based.
I never really got the hang of CIDR addressing but I understood the rationale and concepts of it. I was never very good at finding a good approach to subnetting and CIDR mask determination though. Usually there was a network person’s brain handy to have a conversation with and that got me by.
Then along came public Cloud and the rules for CIDR address allocation and subnetting changed again. I knew that the old approach to subnet determination wasn’t really good for the public Clouds and all the docs from the vendors wanted you to assign a /16 to every VPC/vNet you created. This always felt wasteful and like overkill to me.
I decided to hunt around for something that could help me and found this tool. Visual Subnet Calculator
GitHub Universe 2018: Low Key Revolutionary – James Governor’s Monkchips
— Read on redmonk.com/jgovernor/2018/11/07/github-universe-2018-low-key-revolutionary/
Stumbled upon this page a few weeks back when looking for approaches to how Azure Subscriptions and tenancies can be established and governed well.
via Best practices for enterprises moving to Azure | Microsoft Docs
So today I discovered that if you inspect the Azure AD Connector config via its GUI the config it gives you is actually about 5% of what is actually there. Specifically, the GUI doesn’t display the rules for OU filtering.
To work around this you can use the sync tool to display the OU filtering config. You’ll need to login as your in-prem AD sync user though to do this. If you don’t have those credentials then you can gather the config using the tool below and then turn it into an easier to review HTML output.
Be warned though, a small AD I ran this against produced a 3MB html file of stuff. There is A LOT of items in AADC that average admins wont ever see or hear about.
Microsoft/AADConnectConfigDocumenter: AAD Connect configuration documenter is a tool to generate documentation of an AAD Connect installation.