You can get the Exam Dumps here: https://www.certificationsdesk.com/microsoft/real-AZ-100-exam-questions.html, if you're willing to pay for them.
However, to prepare for any of these exams, there are numerous resources available online. But the challenge is to find the updated resources to keep up with the new features and service offerings by Microsoft.
You can thereof start preparing for the Exam with the help of Microsoft documentation that has immense information along with practical demonstrations.
You can always teach yourself anything and everything with the help you YouTube. Just keep in mind that you choose the latest videos though, as some of the videos may be outdated ( based on MS Azure classic ). You might wanna check out Edureka’s channel to Microsoft Azure Training Videos.
And then you can take practice tests to familiarize yourself with the resources and services offered by Azure. See the Microsoft Certification exam overview for information about registration, videos of typical exam question formats.
Please Note: The exam AZ-100 is expiring on 1st of May. If you attempt the exam before it and pass it, then you'll be awarded the certificate on or around 1st May. But if you're going to prepare for it first. Then I'd suggest you to prepare for AZ-103 as this will be the official exam for Azure Administrator from 1st May onwards.
Hope this helps.