Parse netlogon.log using PowerShell to find missing Subnets
[TL,DR: I’ve written a script to retrieve IP Addresses from subnets not defined in Active Directory. It is published on Technet Gallery: Get-MissingSubnets]
Active Directory uses Sites to define where in the topology a computer resides and thereby determining which server that should be used for certain services. For example sites are used to determine which Domain Controller a client should use as a logon server and if one of my clients log on at a site somewhere in Australia I probably don’t want it to process Group Policies from a Domain Controller in the US.